Wednesday, December 28, 2011

Fast Gold Concentration



Offered here without any sort of endorsement.  It just "popped up" during a YouTube search.  May offer some comments, later.

Monday, December 12, 2011

Accretionary Wedge #41...

Subject: the most memorable or significant geological event that you’ve directly experienced.

Excluding direct weather events, e.g., a tornado, dust storms (including a day-long dust storm waiting for the Space Shuttle to land at White Sands Missile Range), dust devils, and the remnants of a hurricane over the Eagle Mts.,...the most memorable geological event in my memory was the result of a weather event that happened a few miles away - A flash flood in New Mexico.

It was probably 1985, my wife and I went from El Paso to Hillsboro, New Mexico to visit a Labor Day weekend outdoor antique festival. During a previous year, I had a table selling beer collectibles ("breweriana") during one of the festivals and made a small profit. The first few outdoor antique festivals I attended were either on Memorial Day weekend or Labor Day weekend, I might have done the Memorial Day, it has been so long, I don't specifically remember.

At some point, the organizers decided to consolidate to the Labor Day weekend, to coincide with the Aspencade, enjoyed by bikers - you know the Harley-type bikers. There was one bar in town, when it was taken over by bikers, it made for some interesting encounters. The bikers were usually well-behaved during the daytime, as there was a healthy contingent of New Mexico State Police in the streets.

Anyway, after enjoying the festival and navigating the biker-filled bar for a beer, we decided to leave. Afternoon and evening summer time thunderstorms are not unusual in the area.  I don't recall it raining in the town that day, but we were aware of storms in the mountains to the north and east of Hillsboro.  After weaving through the mountains, we approached the last arroyo crossing before a long flat area that led to I-25.  The arroyo was probably 4 or 5 miles east of Hillsboro.

Traffic began to stop and to our left, we could see that parallel to the road, the arroyo was filled with a "healthy" flash flood.  As it was obvious that we weren't going anywhere for a while, I stopped the car and walked a couple of hundred yards down the road to get a better look at the flooded road and the upstream area.  [As there weren't a huge number of cars, it was likely that the flood had only covered the road for maybe 15 to 20 minutes.]  While watching, I observed one or two boulders - probably 3 feet in diameter - slowly tumbling in the muddy water.  They didn't move far, but they did move.  After a few minutes of "wow" - but lacking a camera - I decided to walk back to the car. 

My wife and I had three choices: 1) Wait on the road until the flood subsided and the road was cleared; 2) Go back to Hillsboro and take the southern road from town - several tens of miles extra driving to get to I-25 or I-10 to the south; or 3) Or go back to the bar and have another beer or two with the bikers and then try the same road an hour or two later.  We chose #3.  By then, the road crossing had been cleaned of gravel and cobbles and we continued on our way, back to El Paso.

My uncle in Phoenix had warned me of flash floods well before I moved to El Paso, so if we had been there while the leading edge of the flood was within sight, but upstream from the road crossing, knowing the acceleration qualities of a Chevy Chevette, I probably would have opted to test the brakes and remain on the west bank of the arroyo, i.e., not try to "beat it out".

A Few Field Camp Field Trip Photos

A few of these have been shot by friends during later trips, used because they are digital images rather than scanned slides or photos.  Or because my camera demons prevented my photographing Arches National Park.  They are not presented in the order in which they were visited.

As with other photos, these have been labeled for classroom use.
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Wednesday, December 7, 2011

Field Camp Memories

A Geologist friend commented on Facebook about the National Geographic show "Rock Stars", which I gather to be about engineers. She commented that it was about time that rocks made it to reality TV.

It brought to mind possibilities of an actual Geology-related reality TV series. If my UTEP Geology Field Camp of 1977 was typical, it would make for enough interesting stories for at least a short series - Geologists being the eccentric characters that they are.  [But the problem is, unless the participants forget that there is a camera, they will alter their behavior, i.e., the incidents described below were spontaneous, not scripted or exaggerated for the camera.]

Late next May will mark the 35th anniversary of that summer, the first summer I spent in El Paso. Damn, time flies.  Of note; the statutes of limitation have expired for any incidents described later.  Sadly, I didn't keep up with the names of those non-UTEP students.  One of which - from University of South Carolina - I gave a ride to as far as Atlanta afterward.  1,500 miles in 38 hours with a minimum of stops.

For those that have never experienced a Geology Field Camp, it is about learning and practicing different methods of Geologic Field Methods, mapping, measuring strikes and dips, measuring sections, estimated thickness of layers, etc..  Hours and hours outdoors.  By our last full week, daytime temps were reaching 105 degrees.

Dr. Earl M. P. Lovejoy was a certifiable character.  A big guy, he had a big, booming voice and a good sense of humor, including poking fun at himself.  It was said that he died laughing at a student's joke during a field trip in 1980 (or so).  A massive heart attack left him essentially dead by the time he hit the ground.  He had a wealth of interesting and humorous stories.  I miss those campfire conversations during the 10 day field trip.

An example of his sense of humor - during the 10 day field trip through the Four Corners States, someone found a bleached deer skull and tied it to the leading edge of the hood of one of the Chevy Suburbans.    Someone else took a Sharpie and labeled it "Earl".  Upon seeing it, Dr. Lovejoy pulled out his own Sharpie and added the initials "M.P." to the skull.

In no particular order of occurrence are some of the memories of that field camp and field trip:

Being beaten by the heat.

Spring semester 1977 was my first at UTEP.  I had done well in Dr. Lovejoy's Geomorphology class, making an "A".  He was expecting big things from me in field camp. 

Having grown up in Georgia, I was used to "dripping sweat" during the summer time and compensating for that.  I hated salt tablets and I didn't like Gatorade at the time.  I made do with water (and beer).  In the dry air of El Paso, one sweats without being aware of it, as evaporation keeps shirts dry - for the most part.  After a week or so outdoors, I became fatigued and was not able to recover the lost energy.  As I didn't complain, no one suggested salt tablets or Gatorade and I fell behind with the homework portion of the field camp assignments, turning in several of them late.  I wound up with a "C" in the course without even understanding why.  I just didn't have any energy.  I never got fatigued enough to pass out or to "get stupid" (as I did with later episodes of dehydration/lack of electrolytes), thus my issues were "below the radar" and didn't get resolved.

Dr. Lovejoy's Death March.

During our first week of getting to know the El Paso Geology, one of our excursions was into the western side of the Franklin Mts., north of Tom Mays Park (and Trans-Mountain Road).  I think most of our time was spent in the Ordovician, Pennsylvanian, and Permian sedimentary layers in the area, perhaps some of the Western Boundary Fault Zone was visited, also - as well as a probable discussion of the large landslide blocks in the area.

The problem was, it was a "two canteen" field trip - which I don't recall being announced and one canteen just wasn't enough.  I don't recall plastic water bottles being as prevalent as they are now, so one WWII-era aluminum canteen was all I had.  I wasn't the only one in this position.  It seemed that the last mile of the "death march" was uphill to the truck in the heat of the afternoon.  Again, no one collapsed, but it was one of those times when you could "see collapsing" from where you were.  The student assistants may have had extra water, but it was one of those deals that - if you had to ask for water, you were going to catch hell about it, later.  Rather, there would be much teasing about it. 

Don't know about the origin of the "Death March" name, not to take away from the Bataan Death March, it was simply a humorous was of dealing with it.  I don't know if it was a classmate of that time or someone earlier.

Don't ask me about "bugs".

Dr. Lovejoy's areas of expertise were Structural Geology, Geomorphology, Mapping, Landslides, and related things.  Not paleontology.  Not in the least.  We learned to ask each other, one of the student assistants, or the assisting professor - "What is this fossil?" - out of ear shot of Dr. Lovejoy.  If we lingered during a walk and he thought we were looking at fossils, he had something to say about that.  If we had been in igneous and metamorphic rocks, he might have tolerated questions about minerals, but not "bugs".

Encounters with cicadas.

Most folks - along the way in their lives - have some sort of encounters with cicadas.  In Georgia we have the "normal" Dog Days Cicadas that are active every July - September.  Then as happens every 17 years (or 13 years - whatever) we have the "17 year cicadas" which are more incessant with their droning.  As I didn't spend extensive time outdoors in El Paso during late-May/early June as I did in 1977, I don't know if the cicada "invasion" is the same every year or if 1977 was "special".  I do remember cicadas landing on every vertical object, including standing persons and stadia rods.  Nothing harmful about them, just annoying and their "singing" sounded like being at a jet airport.  It may have just been that special time and place on the west side of the southern Franklin Mts..

Getting yelled at.

Rule Number 1 for Dr. Lovejoy's Field Camp.  Everyone got yelled at along the way.  Just part of the deal.  Usually it was over our lack of plane table and alidade skills or something else that didn't meet with his approval.  Usually the statement was; "This map is terrible.  Why are you in Geology?  Why aren't you in Sociology?"

A little background, as an undergrad at Georgia Southern, in the second quarter there - Spring of 1973, due to a late registration time, Historical Geology was closed out and I was forced to get Sociology as a class.  Didn't want it, didn't need it, but most everything else was closed out.  I found out later that though I was a declared Geology major, the Department Chair didn't yet know me and I should have raised hell about not getting the Historical Geology class.  Too timid on my part.  I suffered through the Sociology class and "partied" a bit too much and had a 59 average going into the final.  I figured that some intense cramming would get me a grade in the 60s or 70s and I would at least pass.  Somehow, despite the earnest study time, I made a 19 on the final.  Out of that Freshman Sociology class of 35 people, there were 10 Ds and 7 Fs.  The teacher was never in her office the next quarter and left the college thereafter.  So instead of an A in Historical Geology, I got an F in Sociology my second quarter.  Seriously damaged my GPA.  Never thought that experience would come in handy, but...

When it came my time to be yelled at (with the standard line), I turned to Dr. Lovejoy and yelled back "Well, I flunked Sociology, what the hell was I supposed to do?"  Reportedly, almost no one ever rendered Dr. Lovejoy speechless, but I did (and became sort of a folk hero for doing so).  He shook his head and walked away, probably chuckling about it later.

Siestas.

The last full week of mapping in the El Paso area as at Mount Cerro de Cristo Rey, which straddles the Mexico/New Mexico border, just west of El Paso.  It is a small Tertiary porphyritic andesite intrusion surrounded by intensely-deformed Cretaceous sedimentary rocks.  There are several of these intrusions in the area, the UTEP campus is situated astride another one.  Whether these were eroded magma chambers for overlying volcanoes is unknown, due to the effects of erosion.

Dr. Lovejoy had spent 13 years mapping the area and he had us checking for errors in his map.  He was wise when he told us that "There is no such thing as a perfect Geologic map."  I have found errors in several maps and I am sure that there are errors in mine.  Anyway, by this time, daytime temps were reaching about 105 degrees. 

When we would check in to pick up our bag lunch, we would usually take a small cooler with Gatorade and/or water (and perhaps a can of beer or two) and go back our chosen mapping area.  Once there was some shade in the afternoon sun, we would often find a rock ledge under which to crawl to take a siesta.  Either Dr. Lovejoy knew student behavior or someone tipped him off as he started going out looking for those taking a siesta - catching several of them - again they got yelled at.  (BTW, I never got caught.)

Damned lechuguilla.

Lechuguilla is a member of the Agave genus and consists of essentially vertical spears vs. the usual radiating spears from a central stem of most yucca.  they are called "Shin daggers" as they are usually fairly low to the ground and not as noticeable as other yuccas.  They are also a hazard if you step over them and don't quite give them enough clearance, resulting in getting speared above your boot in the calf area.

The 10-day road trip.

Though we were expected to take some notes for a final exam, the 10-day road trip was a great relief from the field work just concluded.  Being young, it wasn't much of an issue that the Chevy Suburbans (or whatever they were called) had no air-conditioning at the time, we just kept the windows down.  I think there were 4 Suburbans and a supply truck.  Somehow, those of us of the "hippy" type (think of "That 70's Show") wound up in the last Suburban, which came to be known as the "mass-wasted" group.  We knew that for any stuff we did along the way, we had to be discrete. 

We initially followed the Rio Grande Rift through New Mexico and into central Colorado, then went westward to Utah, then southward through the Four Corners area through eastern Arizona, then back through southern New Mexico.  Stopped at a number of National Parks and Monuments along the way got some great photos - in most places.  Besides the rift, we saw a good bit of the Basin and Range Province, the southern Rocky Mts., parts of the eastern Colorado Plateau, and more...  [Photos will be in a separate post.] 

The forest fire.

I think it was the 2nd day of the trip, when we stopped in a forested area to camp out in northern New Mexico, after we had set up the tents and assigned the "Supper team", several of us went for a walk in the woods with a beer and a "doobie".  We made sure to ash the thing in an empty beer can as we knew the fire danger was high.  After the proper period of relaxation, we returned to the camp and enjoyed the evening meal and after-dinner conversation.  All was good as far as we knew.

The following morning, we packed up camp and left.  Some hours later, we heard a radio report that there was a forest fire in the area in which we had camped.  We knew we had been careful - in our "recreation", but there was that element of fear.  Over the next several days, we kept hearing reports from the fire - with that nagging doubt always there. 

Finally, on the third day of the fire, we heard a radio report that a motorcyclist had claimed responsibility for starting the fire.  He was working on his bike when the engine backfired and set the tall grass afire, spreading from there.  Talk about a collective sigh of relief - from something that we couldn't even talk about while it was happening.

So, what happened to that flaming car?

Somewhere on a mountain road in Colorado, we had taken a roadside break to observe the local Geology and the valley below.  To our amazement, a Ford Galaxie came down the road with a small fire in the area of the rear license plate (where the gas inlet probably was).  We didn't actually notice the flames until he was past us and there was no way to notify him of the problem.  We watched him travel down the road into the town below, never seeing any sign of an explosion or larger fire.  Weird.

That most painful hair-washing episode.

The third night of the field trip was spent in the vicinity of Spanish Peaks in southern Colorado.  After 3 days in the vans, without a shower, the sight of a small creek at least offered us the opportunity to at least wash our hair, if nothing else.  After putting shampoo in my hair, I dipped my head into the creek, not thinking about it being a snow-fed stream.  Immediately my scalp was pounded with temperatures that must have been about 40 degrees F.  It was exceedingly painful.  To make matters worse, shampoo is not formulated to rinse at cold temperatures, which meant that rinsing too even longer than normal.

Five minutes after finishing, it was refreshing, but the transition from "ball-peen hammer" pounding to refreshing was not fun.

The "f__king babies" incident.

This one was not "my experience" but I was a witness...  If memory serves me correctly, the driving chores were shared between the UTEP students and student assistants, with the lion's share of the driving of our Suburban being done by "Bob".  We were somewhere in Colorado, I think.  We were next to last - as usual - in the caravan.  As this was before the days of cell phones and compact walkie talkies, we pretty much had to keep within sight of the vehicles ahead and behind us.  As we had been driving for several hours with no significant breaks, except maybe to listen to a brief Geology lecture about an area, coming into a small town was generally expected to yield a gas/bathroom stop.

As we arrived at a "T" intersection and Bob waited for the chance to turn left, a line of 5 or 6 cars was approaching from the left.  All of them appeared to shift to the right turn lane, so Bob began to pull out.  One vehicle - a Dodge version of the Chevy Blazer (don't recall the vehicle name) did not go into the right turn lane, but continued on the street.  Bob accidentally pulled in front of this vehicle, forcing the driver to "stop short" (but without locking the wheels).  As Bob waved "sorry" to the driver, we noticed her - a very large woman - pound the steering wheel with disgust, but we assumed it was over.

We continued about 1/2 mile then turned into a gas station on the left.  Bob pulled up to one of the pumps and one of the students set the pump handle, then all but Bob walked into the store.  Bob turned and put his back to the vehicle window - to relax - as the offended driver was sliding to a stop in the gravel parking lot.  She spotted Bob and marched over to the Suburban and started screeching about "those are my f__king babies in that f__king truck" (within earshot of the elementary school-aged kids).  She repeated this line several times and was loud enough to capture the attention of most of the people in the store.

Other than apologizing several times, Bob covered his face with his hand and avoided arguing with her - which infuriated her even more.  [We thought she was going to reach in the window and physically drag Bob out - she was big enough.  And Bob was not a small guy.]  After shouting for several minutes (or so it seemed), she stormed off, spinning her tires and scattering gravel, "chirping" the tires as she reached the street.

After she left, Bob walked into the store, approached Dr. Lovejoy and said "I suppose you were wondering what that was all about.", to which Dr. Lovejoy deadpanned "Yeah, I was curious.".  After receiving an explanation, he issued the standard "Well, just be careful from hereon." - or something like that.

From then on, "f__king babies in a f__king truck" became a standing joke, for the rest of the road trip.

An interesting dichotomy.

At one of our camping stops, after dinner when we - the students - were seated around a campfire, several students from a very liberal San Francisco-area college asked if they could sit down at our fire, to which we affirmatively replied "Yeah, pull up a rock" or something like that.  They were on a field trip to study American Indian art.  To be hospitable, we offered them a beer and quietly asked if they wanted to "go for a short walk" - translated, to "share a smoke" with us, to which they affirmatively replied as one might expect.

Afterward, when we returned to the fire - the professors were at another fire, until later - they students commented on how they were warned not to "bring anything" on the field trip, lest they be sent home and flunk the class.

We immediately noticed - but did not comment on - this cultural contradiction.  Students from a liberal San Francisco college were warned to "not bring anything", while nothing was said to us, we were just expected to be discrete (as previously described).  Perhaps it was because the art students were more blatant on campus about their "consumption", but that is just a theory.

The field trip stops.

Without intensely reviewing a map and probably out-of-order, these are some of the places we visited:  Spanish Peaks, CO; Dinosaur National Monument; Canyonlands National Park; Arches National Monument; Mesa Verde National Park; Four Corners Monument; Canyon de Chelly, AZ National Park, Black Canyon of the Gunnison,...there are probably other places currently not remembered.  Getting a Geologic explanation at all of these stops was almost worth the price of the class itself.

Camera demons.

At the time of field camp, I had owned a Miranda Sensorex II 35 mm camera for about 2 1/2 years, with good results.  It was a pretty good camera for its day, comparable with the Minolta SRT 100 series.  I generally didn't carry it with me during mapping and hiking because of the extra weight, but on the field trip it was a necessity.  As this was 1977, the only choice was to shoot multiple rolls of slides and then get them processed upon return to El Paso.

All seemed well the entire trip, but for some reason, somewhere between Canyonlands National Park and Mesa Verde National Park, the shutter jammed.  It sounded normal, thus I had no idea of the problem at hand.  For some reason, it seemed to fixed itself, with the "lost slides" primarily in the Arches National Monument and Four Corners Monument areas - in both areas, I had no slides returned from the lab, just black, unexposed strips of film.  Thankfully, K-Mart (the cheapest way to get the slides done) didn't charge for those screwed up rolls.

[Because of the lost slides, when I had a summer job in Farmington two years later, I made a special trip to Arches and the same thing happened, except it didn't fix itself.  I got hundreds of good slides from the Bisti Badlands of New Mexico, areas around Silverton, CO, and other places, but once I went back to Arches, my camera was toast for the rest of the summer job.  I couldn't yet afford a "back-up camera".]

"It's the plague, it's the plague."

[Sorry, just had to do it.]  When we made one of our last stops, at Canyon de Chelly National Park in eastern Arizona, the first night I chose to sleep out on the ground in my sleeping bag (which I and others had done several times).  The next morning in the bathrooms, I noticed a flyer taped to the wall advising people not to pick up any "easily caught" squirrels, chipmunks, etc., as "the plague" was endemic to the area.  After sleeping out on the ground - with the normal paranoia about rattlesnakes sliding into the warm sleeping bag - you can't imagine how thrilled I was to think about - sleeping on the ground, subject to plague-ridden fleas, ticks, etc..  The next night I slept in one of the Suburbans.

There are probably other memories, I may relate them as they return.  If any readers have noteworthy stories, if the statutes of limitation have not expired, then perhaps change some of the names to "protect the guilty", hehe.

Friday, November 25, 2011

"Brinicles"



Interesting formation of submarine (sub-ice sheet) ice "stalactites" that reach downward and freeze anything in their path on the shallow sea bottom. It might explain mortality-clustering (death assemblages) of certain fossils in the fossil record.

Always something new to observe and learn. Cool.

Not being a marine biologist, I wonder if all of the frozen organisms are dead or are some of them held in "suspended animation" until thawed?

One could also wonder about - in the past - how deep did these things go during protracted periods of cold, i.e., during Ice Ages?

Sunday, November 20, 2011

Etowah River Tunnel Video

About 35 years ago, my Dad and I visited an old mining-related tunnel on the Etowah River (probably in Dawson County). The tunnel itself was not part of a mine, but two different mining companies worked on the project to divert the river through a ridge, so as to mine the river bed for gold.

The "old timers" told them they would not find enough gold in the river bed to pay for the costs - and ultimately they were right. The first mining company started on the upstream side of the ridge, went halfway then went bankrupt. The second company came from the opposite end and met perfectly (horizontally), but there is a 30 inch drop "midway", as the second company's "half" didn't match vertically. That is the source of the "language" at about 2 minutes or so in the video. It is hard to imagine a "first timer" going over that drop without some sort of exclamation.



We were satisfied with visiting the entrance and panning gold from some nearby creeks.

Oh, did I mention it was in January? Riding in 40-degree rain, in an open-top Jeep, was not my idea of fun. We had gone there with a Dawsonville resident and his son (15 year-old with a learner's permit). My Dad and the other guy were in my Dad's truck and as I was the youngest adult in the group (at 21), I was "selected" to ride with the 15 year-old per Georgia law (regarding learner's permits).  It wasn't raining on the trip to the tunnel, but it was on the way back.  I enjoyed visiting the tunnel, but that ride in 40-degree rain was one of the reasons I hate cold weather.  Even with a poncho, it was not fun.

Wednesday, November 16, 2011

Geologist Interruptus

My bad, I have been busy with such things as job hunting and family issues - including a major cleanup of our garage and basement.

Will try to return to blogging, soon. Honest.

Wednesday, October 12, 2011

It's Earth Science Week - Day 4 - Park Photos

Properly labeled geophotos can offer an interesting and useful teaching tools. In some cases, I have managed to convince friends to provide travel photos to cover areas not yet visited. [More meaningful commentary will be added later.]





Tuesday, October 11, 2011

Day 3 - It's Earth Science Week - Badlands and Hoodoos

Just a few interesting landforms - large, medium, and small - courtesy of Mother Nature.







[Explanations and notes, later.]

Monday, October 10, 2011

Day 2 - It's Earth Science Week - Columnar Jointing in Basalt

Will try to post each day of this week.

A fellow Geologist on Facebook posted the "what if" you could make pavers from columnar-jointed basalt. I posted these images on FB, so as to give casual readers an idea of what we were discussing - in some jest. The conclusion was (on my part) that basalt pavers would be neat, but because of access problems and logistics, it probably wouldn't work. The first 3 photos were from park areas, while the fourth is in a Wilderness Study area, 1 mile plus from any parking - even if it was legal.

This particular photo from Yellowstone was a scanned slide, taken by my Dad in the summer of 1980, while he and my Mom were on their last vacation together.  He passed away that November.


A good friend went on a short vacation with his dad, brother, and son and got a number of photos of Devil's Tower in Wyoming. 


The Aden Basalts - flood basalts from fissure eruptions - are located in southern Doña Ana County, New Mexico.

For those not familiar with columnar basalts, they usually form vertical, elongate polygons with 5 - 7 sides, during the cooling of surface and near-surface basalts in flows and volcano necks as you can see here. I seem to remember there being some columnar joints in some parts of the Palisades of the Hudson sill, but don't have any photos.

Sunday, October 9, 2011

Day 1 - It's Earth Science Week - What Can You Do?

One of the best ways to celebrate Earth Science Week (Oct. 9-15), is to show some appreciation to Earth Scientists.

 Here are some ideas:
  • Take an Earth Scientist to lunch.
  • Be patient with our eccentric ways.
  • Understand that just because we may not have books on sale at Barnes & Noble, that doesn't mean that we aren't writers. We are sujbect to "writer's block" and when the "dam bursts", we may need to write down our thoughts before we lose them.
  • Be empathetic with us - as during decades of travel with others - we pass thousands of rock outcrops and other sites of interest, without stopping.
  • Just because we talk to ourselves, we are not necessarily crazy, we may be rehearsing a lecture or an explanation of a particular scientific issue.
  • It is OK if we say "I don't know".  It doesn't mean we are not looking for an answer.
  • Part of being a scientist is observing things and seeking an explanation.  Don't be surprised if we take an interest in things outside of our particular discipline.
  • Many of us have a never-ending "yearning to learn", so please don't be offended (or surprised) if we bring a textbook or small reference book with us during a casual lunch.  We may be trying to reach a "learning plateau" on a particular subject, in case the opportunity arises to offer an educated opinion.
Other things may be added, as they come-to-mind.

Friday, October 7, 2011

Gold Fever Flows On



From each one of the sluice videos, you can get some ideas, if you are interested in building your own.



Turbopan, hmmm.



A test of a highbanker, designed to speed up the removal of larger gravel.



Gold Grabber, another good idea.

More Low-Grade Gold Fever

I have never owned or used a sluice box, but I am getting a "hankering" to build one. As a reminder, you have to remember to check on the status of the stream, so as not to get hammered for violations of regulations.

Also as I said previously, it is best to try to avoid excessive environmental damage. Try to restrict your digging to the active channel and eroded material along the margins (if old creek gravels are being eroded).

Still Nursing a Low-Grade Gold Fever

Panning with Jayda, not your stereotypical gold miner. You can see in the early part of the video that this is not a casual operation. And as I am "environmentally aware", I am concerned about excessive disruption of streams - by digging into the banks. Digging in the channel itself (and in the eroded material from the banks) is not much different that what nature would do during a heavy storm.

But this appears to be the floor of an old mine, the environmental damage has already been done. Or maybe it is an active mine.



She knows what she is doing, I wish her luck in her endeavors. (I wonder where she is?)

Wednesday, October 5, 2011

What Was the Pleistocene? [Original Post Date: 10/25/05]

Before we get to the issue of the Pleistocene re-wilding of North America, some may be wondering "just what exactly does "Pleistocene" mean?

"Pleistocene" refers to a specific interval of geologic time that is estimated to have lasted from 1.8 million years ago to 10 thousand years ago. It is best remembered as being the time of the last major Ice Age. Many scientists believe that "today's" warm climate is simply a natural rebound (or recovery) from the last Ice Age.

Referring to the accepted Geologic Time Scale (different versions may have slightly different age estimates), geologic time is divided into a hierarchy of time periods, based on different criteria. Most of the time boundaries are based on significant changes in the sedimentary rock and fossil record, as observed in 18th and 19th century Europe, where most of the present Geologic Time Scale was devised and defined. All of the time units, within the various categories, are of differing lengths.

The broadest time periods (at the top of the hierarchy) are "Eons", which cover hundreds of millions of years. We live in the Phanerozoic Eon, which began approximately 544 million years ago with the first widespread appearance of hard-shelled marine organisms.

Eons are divided into "Eras", which cover tens of millions of years. We live in the Cenozoic Era, which began approximately 66 million years ago with the end of the Mesozoic Era, when the dinosaurs became extinct.

Eras are divided into "Periods", which cover millions to tens of millions of years. The Cenozoic Era consists of the Tertiary Period (66 million years ago to 1.8 million years ago) and the Quaternary Period (1.8 million years ago to the present).

Periods are divided into "Epochs", which cover hundreds of thousands of years to millions of years. The Quaternary Period consists of the Pleistocene Epoch (1.8 million to 10 thousand years ago) and the Holocene (or Recent) Epoch (10 thousand years ago to present). The dividing "line" between the two epochs is the last major ice age.

As details of the geologic record become less distinct as we go back in time, the Epoch time classification is only used on a world-wide basis for the Cenozoic Era, i.e., the last 66 million years.

With the mass extinction at the end of the Mesozoic Era (and the end of the Cretaceous Period, too), approximately 66 million years ago, the niches and habitats of the world's ecosystems were "emptied out" of dinosaurs and other organisms. The mammal and bird survivors refilled these vacant niches and habitats with an "Adaptive Radiation", i.e., whereas the previous Mesozoic Era is known as the "Age of Reptiles", the Cenozoic Era is known as the "Age of Mammals".

With the natural global warming that ended the last Ice Age, human populations rapidly grew, cultures developed and humans migrated, in our case, most notably from Asia into North America. There was a significant extinction of large Pleistocene mammals in North America, attributed to human activities by some scientists, while others consider other possible causes (but not excluding the "human effect").

The article linked at the top of this post addresses the plans to introduce large African and Asian mammals (megafauna) to North America, to "replace" that which was lost in the last 10,000 years or so.

A Report on the State of the Geoblogosphere...

is discussed on the German blog Geonetzwerk which presents;

..."data from an online survey with 78 participants and from analysis of more than 200 Earth science blogs.

Our survey shows that a majority of persons writing geoblogs are young, male, and academic. Most live in the USA and Europe. Collectively, their main motivation to blog is to share knowledge and to popularize the geosciences. Blogging is also seen as an opportunity to improve the authors’ writing skills, perform outreach, establish new contacts, and positively influence their careers. The rapid dissemination of news has been cited as an important advantage of the geoblogosphere."...

A little history:

..."The first geoscientific blogs were released in 2001 with “Green Gabbro” (Bentley, 2008) and in 2003 with “Andrew’s Geology Blog”. Building on the term “blogosphere”, blogging geoscientists soon established “geoblogosphere” as shorthand for the entirety of the geoblog community, including bloggers and readers.

In January 2010 the “Geoblogosphere News” aggregator by Huber et al. (2009) had tallied 265 blogs dealing with Earth sciences. This represents an increase in the size of the geoblogosphere of more than 100 % compared to the previous year."...

For what it is worth, my original blogging began in February 2005, though it was a hodgepodge of science, politics, culture, etc., so for that reason, it probably doesn't fit with the proper geoblog definitions of some.

There are some concerns - as there would usually be with a wide-open free-for-all atmosphere. Freedom can be messy.

..."Serious concerns about the credibility and trustworthiness of science blogs have been raised (Ashlin & Ladle, 2006). But no systematic approach to characterize the geoblogosphere has been carried out yet. Similarly, the geoblogging phenomenon has been incompletely documented. What is the geobloggers’ motivation to write? What is their background, both societally and scientifically? What are their information sources? How do they assess the benefits and disadvantages of blogging? What role will geoblogging play for the future working of the Earth sciences?

The first data on geoblogs were collected by Bentley (2008) who conducted a short online survey with 46 participants representing approximately 50 % of the geoblogosphere at that time (Geißler, 2009). Another geoblog-survey was started in August 2009 (female participants: n = 91) to investigate geoblogs as a resource and social support network for women geoscientists (Hannula et al., 2009a, 2009b; Jefferson et al., 2010). This survey included bloggers (n = 36) and blog readers.

With the rapid development of geoblogging, the authors extended and reissued the survey of Bentley (2008), supplemented by data from statistical and semantic analysis of more than 200 Earth science blogs. The study presented here is the first comprehensive attempt to characterize the geoblogosphere from the bloggers’ point of view."

Some other considerations:

..."Blogs have potential to be used as educational tools. In the past several years, several studies have shown that blogs support collaborative, participative learning (Agostini et al., 2009; Hall and Davison, 2007), increase student and teacher relationships, improve flexibility in teaching and learning (Ferdig and Trammell, 2004), and teach students the art of scientific argument (Moore, 2008). In the geosciences specifically, blogs can be powerful instruments to visualize geological phenomena, present annotated field trip guides, or accompany geo-educational projects like “Earth Learning Idea”, which supports teachers and teacher-trainers with Earth-related teaching ideas (King et al., 2008a, 2008b).

The fact that more than 78 % of the surveyed geobloggers write their blogs to acquaint laymen with geosciences suggests that geobloggers see blogging as being a form of geoscientific outreach work. One geoblogger wrote: “The whole goal of being a research scientist is to get your research out as quickly as possible to the widest possible audience. A well-known blog lets you do that very effectively. Our ideas reach people that they would never reach if they were only in our formal publications, and also act as a “gateway drug” to get people onto those publications where the ideas are worked out with full rigor.” Wilkins (2008) reached a similar conclusion; he argued that blogging should be understood as fundamentally outreach for science.

Meanwhile, public geoscientific institutions and societies focus more and more on blogging to increase their visibility to other geoscientists and to a wider public (e.g., AGU, 2010). This includes, for instance, blogs maintained by geological surveys, blogs about research expeditions, and conference blogs. The latter issue has been discussed by Bradley (2009) with the result that he evaluates conference blogs as more advantageous than not."...

Not as much as I should, I sometimes use this blog and my college blog as a teaching tool. I usually leave this blog for the more in-depth discussions or for things not discussed in class.

[For the sake of brevity, you should visit the original linked post for the "rest of the story. For what it is worth, I don't recall if I participated in the original survey or not. At that time, I had not "spun off" this (largely) non-political geoblog, so the politics of the original may have put some people off. We are what we are...]

Thursday, September 29, 2011

A Bit More About Gold Sluicing

A Renewed Interest in Gold Panning...

is sweeping across America's "gold fields", i.e., places that have historically produced placer gold.



Here is a video from "Rock Raiders" - linked on The Blaze website - of all places. Part of the renewed interest is due to the increased cost of gold, another would probably be the higher unemployment rate leaves people with more time on their hands for such endeavors.

I have been out three times this summer with the Allatoona Gold Panners, visiting 2 different creeks in Cherokee County (or extreme North Cobb County), Ga.. I have found something in virtually ever pan, but it is mostly "flour gold", very small grains. The main idea is to have some fun - which I have. I also enjoy accumulating heavy minerals for use in lab classes or just to look through, under a microscope.

Here are a couple more videos:



From Arizona:



Here is an ad for a sluice system - sounds good, but one would need to check for local restrictions regarding the use of sluices. This Grizzly Sluice is cool, but it is a bit pricey - for the hobby miner. The MSRP is $547.00, at this website.



Here is a homemade sluice box:



Another accessory - a homemade "high banker", designed to quickly wash out the larger gravels:



American ingenuity, ya gotta love it! As a reminder, if there are any diamonds, they will be retained in the heavy mineral concentrate, so check it carefully.

Friday, September 9, 2011

The Okie Dokie Diamond [Original Post Date: 3/13/06]

[Call it blog-post recycling or posting of "greatest hits", I am gradually transferring older posts from another blog, as time permits.]

Many people may not be aware of it, but Murfreesboro, Arkansas is the only place in the entire world where common people can pay a small fee and search for diamonds and keep everything that they find. All other diamond producing areas are owned/controlled by large corporations or governments.

From MSNBC News, an Oklahoma State Trooper, visiting the Crater of Diamonds State Park, near Murfreesboro, Arkansas, with his family - for the first time - found a 4.21 carat, canary yellow diamond, that is said to be flawless. Talk about beginner's luck!

The park is approximately 37 acres of ground that is periodically plowed. Visitors are allowed to crawl about on their hands and knees, that is how I found my small white diamond (.37 carats) on my first visit in 1973. There are other areas where people can dig and sieve sand and gravel in water to look for diamonds.

When I was there in the spring of 1978, a couple from Dallas was looking in the same area as I was looking. I left in the mid-afternoon to do some other things in the area. At dusk, I was parked along the road into town, looking for old beer cans in the woods when the Dallas couple recognized my truck and pulled over. They asked me to take a look at what they found and to tell them if it was a diamond. It was a 4 carat, brown diamond, not of gem quality, but with the classic octahedral diamond shape. I got to hold it and I was the first one to confirm that it was a diamond (the park office had closed for the day). I later saw a short newspaper article in a Dallas paper, wherein that diamond was valued at $4,000 because of its size, classic crystal shape, and it being an American diamond. And that was 1978.

The article mentioned that 84 diamonds have been found so far this year. When I was first there in 1973, they said about 250 diamonds per year were found by visitors. Most of them are not gem quality, but once in a while, someone finds a "blockbuster" of a diamond, worthy of faceting and mounting in jewelry. The three main colors at the Crater of Diamonds State Park are white (60%), brown (21%), and yellow (17%) - according to the linked site below. 383 diamonds were found in 2004 and 536 in 2005. The higher numbers than the 1970s may be partially a function of higher numbers of visitors and perhaps more serious methods of searching, perhaps more digging and less crawling.

As mentioned above, it is an Arkansas State Park, open to the public. The state of Arkansas has toyed with the idea of selling the property to mining company, but public pressure has so far preserved the status quo. I know that Libertarian/Conservative purists disapprove of government ownership of land, but this place is so unique, I think it should stay as a state park.

The first diamonds were found 100 years ago, when the area was a farm. The farmer, when dressing out chickens to eat, found shiny stones in their craws (not having teeth, some birds swallow small stones to aid in the digestion process and the shiny nature of the diamonds caught the eye of the chickens). The stones were identified as diamonds, but there were never enough to support a mining operation, so it became a tourist attraction. In 1972, it became a state park.

If you click on the Park link above, the middle-aged black man in the center "works" at the park. Every day the park is open, he is there to pay his fee and that is what he does all day, dig for diamonds. He was there the last time I visited the park in 1983 or 1984 and I talked to him briefly. He doesn't find a diamond every day, but he finds enough to scratch out a living. Some of his diamonds may be among the Arkansas diamonds for sale on this website.

If you ever go there, don't expect to find a diamond, but there is always a chance. There are other minerals of interest to kids, quartz crystals, amethyst, calcite, peridot, agate, conglomerate (a type of sandstone composed of rounded river pebbles) and other minerals. Just keep everything that might even look like a diamond<, and the rangers at the park are more than glad to look over what you have found and tell you "what's what".

Only in America

The Pleistocene Ice Ages [Original Post Date: 3/26/06]

Currently, as defined by geologists, we live in the Cenozoic Era, Quaternary Period, and Holocene Epoch (since the last 10,000 years or so).

The previous epoch was the Pleistocene, which lasted from approximately 2 million years ago to 10,000 years ago. Before the Pleistocene Epoch was the Pliocene Epoch, which lasted from approximately 5 million to 2 million years ago.

Most people have a vision of the Pleistocene climate as being a single large Ice Age, when in reality there were several periods of glacial advance, separated by shorter interglacial periods, some of which were as warm or warmer than today's climate. The primary, attributed reasons for the fluctuations were variations in Earth orbit, Earth axial tilt, and variations in solar output. Some of these fluctuations exaggerate each other, while others moderate each other. Random events such as large volcanic eruptions may play a role, also. Evidence suggests that the global cooling began in the latter part of the Pliocene.

Some authors suggest that the emergence of the Isthmus of Panama (above Sea Level) during the Late Pliocene played a role in the cooling of the climate. Prior to the emergence of the isthmus, there was a narrow seaway that allowed the movement of warm waters from the Caribbean into the east Pacific. The closure of this seaway altered oceanic currents, while opening a land bridge that allowed the migrations of mammals between North and South America.

This series of slides is from a lecture on glaciers. Proceed forward to cover the Pleistocene. There have been previous periods of global glaciation, but those were before humans. Oxygen-18 isotopic data is one type of proxy data used to reconstruct paleoclimate history, including the Pleistocene data listed here in Wikipedia.

From youngest to oldest, as identified in North America, the Pleistocene glacial stages were:

Wisconsinan Glacial Stage
Sangamonian Interglacial
Illinoian Glacial Stage
Yarmouthian Interglacial
Kansan Glacial Stage
Aftonian Interglacial
Nebraskan Glacial Stage
Pre-Nebraskan

Slide 37 shows reconstructed temperature curves for the last billion years and the last 2 million in more detail. Slide 38 shows the maximum extent of the Pleistocene continental ice sheets. Slide 39 shows estimated sea level for the last 20,000 years. These particular slides are from the University of Portland.

After each glacial stage, the interglacial represented a period of natural global warming, a period of rebound. Since the end of the Wisconsinan Glacial Stage approximately 10,000 years ago, there have been several alternating shorter periods of warming and cooling.

Previous ice ages include:

A poorly-documented, possible ice age from 2.7 to 2.3 billion years ago, during the early Proterozoic Era.
The earliest, well-documented ice age was during the late Proterozoic Era, from approximately 800 million to 600 million years ago.
Late Ordovician Period 460 million to 430 million years ago.
Late Carboniferous Period to Early Permian Period 350 million years to 260 million years ago.

From this above-linked Wikipedia article:

..."The present ice age began 40 million years ago with the growth of an ice sheet in Antarctica, but intensified during the Pleistocene (starting around 3 million years ago) with the spread of ice sheets in the Northern Hemisphere. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000 and 100,000 year time scales. The last glacial period ended about 10,000 years ago."

This Wikipedia link shows temperature trends during the last 5 million years.

The Pleistocene Epoch is the recent geologic past. If there were repeated periods of natural global cooling and global warming then, why are people so convinced that any and all unusual changes and variations are triggered by humans?

10.5 Apocalypse...Probably Not [Original Post Date: 5/22/06]

As we proceed (lurch) towards 2012, it is possible that TV networks may rerun some of these recent-past disaster movies, especially during Sweeps Months. It is cheaper than creating new ones.

[Originally posted on 5/22/06 on another of my blogs. Modified slightly for today's "consumption".]

I don't know if any of you have checked in on the NBC 3-part disaster flick "10.5 Apocalypse" (Saturday, Sunday, and this upcoming Tuesday), where the Western U.S. goes to hell in a geologic handbasket. It has just enough science to be interesting and I am waiting to see how much of the Western U.S. is laid waste.

As for likelyhood of the envisioned chain-reaction of earthquakes, volcanic eruptions, sinkholes, etc..., it answer is...

Probably Not!

[Without my Physical Geology textbook here for refresher sake, I am going from memory.]

Plate Tectonics is driven by vertical convection currents in the Asthenosphere, a semi-molten layer beneath the rocky crust (the Lithosphere). So imagine conveyor belt systems upon which the continental plates ride "piggyback". Where there are Asthenospheric "upwhellings" of molten material, if these are upwhellings are linear, they split the overlying crust and push the plates apart. This is what happens beneath the Atlantic Ocean in regards to the Mid-Atlantic Ridge and also in the Eastern Pacific Ocean with the East Pacific Rise. So there are upwhellings of intense heat in the Mid-Atlantic Ocean and the East Pacific Ocean.

In the last 30 million years or so, the North American Plate has pushed over and distorted a portion of the East Pacific Rise. A portion of the East Pacific Rise is present North of the Mendocino Fracture Zone, off the coast of N. Calif., Oregon, Washington, and British Columbia. Here the Juan de Fuca Plate is sinking beneath the North American Plate. The sinking Juan de Fuca Plate is remelting and that is what causes the occasional NW U.S. earthquakes and the Cascade Volcano eruptions (including Mt. St. Helens).

South of the Mendocino Fracture Zone along the Pacific Coast to south of the southern tip of Baja California, the coastal area is dominated by the San Andreas Fault Zone, which is where a small portion of the Pacific Crustal Plate is sliding past the North American Plate. Inland from this area, the mantle upwhelling (mantle plume) is under the continent and may be responsible for the hot spot vulcanism (San Francisco volcanic field (Flagstaff area), the Long Valley Caldera in Calif., Yellowstone in Wyoming, and perhaps the Rio Grande Rift).

The Rio Grande Rift represents a thinning of the continental crust from the El Paso area northward into central Colorado. If the continent were to be rent asunder, per the movie, this would be a natural "weak spot", as the crust appears to be thinned, based on heat-flow data, seismic surveys, and the presence of young volcanic rocks from the Potrillo Volcanic Field in Southern New Mexico, northward along the river.

The "geophysics" of the areas under the continent are different enough that stresses probably are not going to be quickly transferred from one area to another.

Another issue brought forth in the movie was the "Accelerated Plate Movement" theory as proposed by the discredited geologist father of Kim Delaney's character, Dr. Samantha Hill. If the plate motions were to reverse themselves, I would be looking at what was going on along the Mid-Atlantic Ridge. Had one of the plates started to sink in relation to the other? That would signify the reversal from an upwhelling to a subduction zone, where one plate was sinking beneath another.

Mantle upwhellings have stopped before, but we presume it takes millions of years to transpire. And I don't recall any mention of a mantle plume beneath the Western U.S., in the movie. Dr. Samantha Hill's character makes mention of "Sub-Asthenosphere" earthquakes, but to my knowledge, the "plastic" nature of the Asthenosphere makes seismic wave propogation unlikely. The most damaging earthquakes, by conventional wisdom (and supported by data) originate in the upper 100 km (60 miles) of the crust.

The deepest earthquakes are associated with the deep Pacific Ocean subduction zones and some of them originate from as much as 700 kilometers below the surface. With these deepest of earthquakes, the seismic waves are associated with the sinking oceanic plate, which though partially-melted, still retains enough rigidity to transfer stresses.

So, in summary, there are an endless number of "what ifs" and things that geologists and geophysicists dream of seeing (for the sake of learning), in this movie, and while anything is possible, it ain't likely. Remember, it is Sweeps Month.

A Follow-up on the Previous Caldera Post [Original Post Date: 8/31/06]

the ABC special did a pretty good job of explaining the basics.

In the case of the Yellowstone Caldera, it is thought to overlie a "mantle hotspot", as does Hawaii, where a particularly strong upwhelling brings heated magma towards the surface. As the magma body rises through the continental crust, it partially melts the crust, adding significant amounts of quartz, and other silica-rich minerals, such as muscovite mica and orthoclase feldspar.

From the above-linked USGS webpage:

"...Scientists infer that rhyolite lava flows as well as the caldera-forming ash-flow tuffs were fed from shallow magma chambers filled by the melting of rocks of the lower continental crust below Yellowstone. The heat needed to facilitate the melting process was supplied by the repeated injections of basalt magma from the mantle into the shallow crust."

As mentioned earlier, these silica-rich minerals make the magma more viscous. As the magma rises, the pressurized fluids (mostly mineral rich water) "wants to boil". Even though more silica-rich eruptions are the norm, from time to time, basalts can also erupt. The basalts are derived from the mantle below and when erupted, it is because the basalt has moved through the crust quickly enough not to melt much of the crust. [Note: The higher-temperature basalts can easily melt the silica-rich minerals,which crystalize at lower temperatures, than do the minerals in the basalts.]

These are large magma bodies, termed "batholiths" that become magma chambers for the overlying eruptions when they reach shallow-enough depths. More than 100 square miles is usually bulged by the rising magma.

When the buoyancy (sp.?) and the gas pressure of the magma overcomes the strength of the overlying rock, as depicted on the program last night, eruptions will break through in several places. These multiple eruptions taking place at the same time will produce gas-driven pyroclastic flows and partially drain the magma chamber. The magma chamber will then collapse inward, opening up a circular to round "ring fracture" system, which will provide more conduits for molten rock to reach the surface, likely triggering even more eruptions. Some of the eruptions may be restricted to the collapsed crater, while others will erupt outward.

Watching the pyroclastic flows from the smaller composite volcanoes gives an idea of the speed of these types of eruptions, but the caldera eruptions may be two to three orders of magnitude larger.

ABC Discovers Calderas [Original Post Date: 8/30/06]

[Posted originally on another blog of mine.]

Or by another name "supervolcanoes". There are two active calderas or cauldron-type volcanoes (very large volcanoes with huge oval shaped craters) the lower 48 states, the Yellowstone Caldera and the Long Valley Caldera (eastern California). The oval crater for the Yellowstone Caldera measures approximately 36 miles X 48 miles and has erupted three times over the last 2 million years or so. The last major eruption was approximately 630,000 years ago.

The Cascade Volcanoes (Mount St. Helens, Mt. Rainier, Mt. Baker, etc.) are a smaller type of volcanoes, called composite volcanoes. Both types of volcanoes, calderas and composites are both capable of producing pyroclastic eruptions, which are the explosive eruptions which consist of gray clouds of superheated gases, volcanic ash, rock fragments, crystals, and pumice fragments, that are capable of moving across the countryside at speeds of up to 125 mph. Ancient pyroclastic flows (also called ash flows) have been traced from composite volcanoes to a distance of 60 miles and from calderas a distance of 100 miles. Once the ash flows begin their travel, a trapped layer of air beneath them serves as a cushion, allowing for less friction and greater travel distances.

These types of eruptions occur in composite and caldera eruptions because of the presence of silica (quartz) in the magmas. Quartz tends to increase the viscosity of magmas and as the magmas rise towards the surface, the quartz makes the magmas "want to freeze", while the trapped gases and liquids "want to boil". If the viscous magma plugs the volcano neck, pressure builds until the immovable object is overcome by the irresistable force, which results in an often catastrophic explosive eruption, a la Mount St. Helens, Mt. Pinatubo, El Chichon, Krakatau (1883), Mt. Vesuvius, etc....

As explosive as composite volcanoes are, calderas are much more so, as the quartz content is usually higher, i.e., the underlying magmas are generally similar to granite and the calderas are usually larger. Another caldera, which is approximately 1 million years old is the Valles Caldera, near Los Alamos, NM.

ABC is televising a special tonight [8/30/06] (9 PM EDT) called "The Last Days on Earth", which among other disasters, focuses on the damage that might be done to humanity by a large caldera eruption. The last major caldera eruption occurred about 74,000 years ago. That particular eruption of Mt. Toba in Indonesia reportedly put a major hurt on the DNA of early humans, i.e., there were mass casualties, apparently.

[As with typical Indonesian volcanoes, Mt. Toba was probably a large composite volcano, the explosive eruption of which triggered a caldera collapse. That is somewhat different from the caldera-type "supervolcano" mentioned in the first paragraph.]

Wednesday, August 31, 2011

Discovery of Evidence of the Oldest Land Plants in Argentina

While looking up info on Liverworts,...

From a BBC article from October 2010:

Paleobotanists have recorded evidence of at least five different types of non-vascular plants - similar to Liverworts - in the form of cytospores from the Early/Middle Ordovician of Argentina.


From the article:

..."These spores, dating from between 473 and 471 million years ago, come from plants belonging to five different genera - groups of species.

"That shows plants had already begun to diversify, meaning they must have colonised land earlier than our dated samples," said Dr Rubinstein, who made the discovery with scientists at the National University of Cordoba, Argentina and the University of Liege, Belgium.

The researchers' best estimate is that the colonisation of land could have occurred during the early Ordovician period (488 to 472 million years ago) or even during the late Cambrian period (499 to 488 million years ago)."...

..."The previous record holder of the earliest known land plants were small liverwort cryptospores found in Saudi Arabia and the Czech Republic.

These were dated at 463 to 461 million years old."...


A bit more:

"The cryptospores from Argentina hint at where land plants originated.

"It most probably happened on Gondwana, as already demonstrated by previous discoveries, but very far, at least 5000km, from the Saudi Arabian and the Czech Republic, where previous earliest traces of land plants were found," said Dr Rubinstein.

As land plants matured, they evolved from liverworts into mosses, and then into plants known as hornworts and lycopods.

Then ferns appeared before seed plants, of which there are many species today, finally evolved."

Sunday, July 31, 2011

Accretionary Wedge #37 - Sexy Geology

No, Geology is not a fetish for me. Sometimes an obsession, but not a fetish - there is a difference.  Without going into any unnecessary detail, I will just list my favorite rock units, as this part of AW #37.

For photographic purposes, I related my "current love" for the Jurassic Navajo Sandstone, in my "What a Geologist Sees - Part 36".  I haven't been in the outcrop area of the Navajo Sandstone for many years, but through some of my old 35 mm slides and digital photos given to me by friends - I have developed a great appreciation for the eolian cross-beds and the diverse settings in which the Navajo is exposed on the Colorado Plateau.

For fossil-collecting purposes, I would have to say that the Late Eocene limestones of the Georgia Coastal Plain and the Florida peninsula.  Of greatest interest - to me - are the diverse array of irregular echinoids with a small, but nice assemblage of different scallops (Chlamys and Pectin sp.).  On a smaller scale, there are also small comatulid crinoids and very small brachiopods at some of the localities.  In the Savannah River area of Burke County, there are occurrences of the large oysters Ostrea gigantissima in the Griffins Landing Member of the Late Eocene Dry Branch Fm.

The widespread distribution of limestones (close to the Fall Line) and other evidence suggests that the Eocene, especially the Late Eocene was a time of warm temperatures, friendly to biodivesity.  The Ocala Limestone in Florida is the dominant Late Eocene rock unit in Florida.  Updip in Georgia, there are a number of different limestone units of interest, as well as the sandy Clinchfield Formation.

The first Late Eocene locality that I visited was the Tivola Limestone, in the Perry, Ga. area, in Houston County.  This sand dollar was from that undergrad field trip, from the old Medusa Quarry, SE of Perry.  This sand dollar is also found in the Tivola-equivalent at the Rich Hill quarry, just 2 miles from the Fall Line, NW of Macon.

Unless there have been some interpretational changes in the strat sections, the Sandersville Limestone is one of the youngest of the Late Eocene units in the Georgia Coastal Plain and the Periarchus quinquefarius was the last of the 3 (or 4) Periarchus species in Georgia.  The Ocmulgee Fm. is a downdip equivalent of the Sandersville.  Periarchus lyelli, from the uppermost part of the underlying Middle Eocene Lisbon Fm. and the Clinchfield is the first of these, followed by P. pileussinensis, then P. quinquefarius.

This smaller irregular echinoid is from near Leesburg, GA, in the old Starkville quarry.  If memory serves me correctly, this is the equivalent to the limestone exposures at the northern end of Albany, near the "power dam" on the Flint River.

I traded for this specimen from the Florida peninsula.  There are numerous other Late Eocene echinoids in my collection, and there are other Georgia collecting localities, some now inaccessible.
Presumably, it was the end-of-Eocene Chesapeake bolide impact that triggered a regional extinction event, which wiped out a number of the Late Eocene echinoid taxa or at least those in certain updip facies. 

Yeah, I guess I am sort of in love with the Late Eocene of Ga. and Fla.  Just don't tell my wife.

[Update:  I seem to be having trouble with my Blogger account, it is giving me grief when I try to comment on my own post.  So thanks to all that leave positive and useful comments.  I am not ignoring you, the system just has a glitch.]

Saturday, July 30, 2011

Accretionary Wedge #37 Seeking Posts on - Sexy Geology...

August 26th is the deadline for your photos and stories of "Sexy Geology".

The host site - "Outside the Interzone" describes the desired type of story as: "...geology that makes your heart race, your pupils dilate. Rocks and exposures that make you feel woozy and warm. Structures and concepts that make your skin alternately sweaty and covered with goosebumps. Places you've visited, read about, or seen photos of that make you feel weak-kneed, and induce a pit in your stomach."

The original Accretionary Wedge site has this link on the subject.

This brings forth some interesting thoughts and I will try to have something, soon. Without getting "racy", that is. People think we are crazy enough as it is.

[Note: For what it is worth, to avoid any confusion, my regular "What a Geologist Sees" Parts 36 & 37 happen to chronologically coincide with Accretionary Wedge Posts #36 and #37. This is by shear accident.]

Tuesday, July 19, 2011

What a Geologist Sees - Part 36 - The Navajo Sandstone

[A minor disclaimer - I am not 100% sure that this is the Jurassic Navajo Sandstone, there are other eolian sandstones in southern Utah, but I am going with the assumption that this is Navajo.]

This "wow" photo was taken earlier this summer by a couple from our church while they were on vacation in Colorado, Arizona, and Utah.  They were kind enough to give me copies of their photos for educational use (and those will be captioned and attributed).  As my budget and schedule doesn't permit such excursions, I am grateful for their photos - past and present.  This is their first "digital trip", as past trips have been photographed on 35-mm film, necessitating scanning of prints or slides. 

The above photo was taken along Utah Scenic Byway 12, somewhere near Zion National Park.  This couple - Bob and Jenny - are very good about creating scrapbooks and logs of their travels and collecting all sort of info from the National, State, and local parks that they visit.  But sometimes it is some of the "in-between" photos that are hard to locate (or else I can't find the same scenes photographed by other people - for ID purposes).  I have several other great photos (for educational purposes) of the Navajo Sandstone.

This is another of their photos from this year, of "Checkerboard Mesa" in Zion National Park.  An image of Checkerboard Mesa used to grace the cover of one of the Physical Geology lab manuals we used to use.

This photo from Upper Antelope Canyon (from a scanned negative) is from a previous western trip.

Though I haven't visited any outcrop areas of the Navajo Sandstone for years (decades), from my past photos and newer photos given to me, I would have to say that the Navajo Sandstone is my "favorite" sedimentary unit for photographic purposes. I don't know of any fossil-laden areas of the Navajo, it is the large-scale eolian cross-beds that make for great photographs and educational teaching tools.

[BTW, for fossil-collecting purposes, I would have to say that the Eocene Ocala Limestone (and similar-aged units in Georgia) is my favorite sedimentary unit.]

Saturday, July 16, 2011

Accretionary Wedge #36...Stuff Left Behind, With Regrets

What have you left behind in the field? What have you lost or what do you regret not having collected, including photographs?  [Before going further, I would like to thank all of the participants.]

The first contributor, Evelyn Mervine recounts some fascinating field work in the Indian Ocean, then she goes on to relate what she regrets not bringing home - a baby goat or a baby camel from Oman. I wonder what U.S. Customs would have had to say about that? [I once used a large paper cup to catch a kangaroo rat (for a few minutes) in the Eagle Mts. of West Texas, but it wouldn't have acclimated to a caged existence.]  If one lived on a farm, bringing home such "souvenirs" from the field might work, but not so sure in a two-bedroom apartment.  I don't know whether goats and camels can be housebroken.  Here is her post in its entirety. 

From Ann's Musings on Geology, Ann muses on her extensive 35-mm photographic past and photos she didn't get. She recounts such issues as not wanting to expose her camera to adverse conditions, e.g., dust or rain or not wanting to carry the extra weight. [Been there, done that on both counts.] She also described the familiar college-student issues, such as the expense of film purchases and development costs. As I did, she chose slides as they were cheaper. Another constant issue with 35-mm film photography, you had to wait to know if you got one or more decent shots.  Many times, once she found out that she didn't get a good photo, it was in a situation where there were no do-overs, no chance to revisit the site.  [Another 35-mm hazard - forgetting to reel the film back into the cartridge before you open the back of the camera.  In 1982, I lost all of my Wisconsin glacial features slides when I did this.]  As I do, she now faces the dilemma over what to do about all of those slides and how to convert them.  Hopefully this can be resolved in a satisfactory way, with a scanner of some type.  [I have a scanner, but not the time.]

Dana Hunter also reminisces about the Photo Not Taken. Actually of the photos not taken when she lived in Arizona. The empty photo-box syndrome. I can attest that there is plenty of good geology to be photographed in all of Arizona, especially the northern half of the state...San Francisco Peaks, Page, Sunset Crater, Grand Canyon, Sedona, Jerome, Barringer Crater, Canyon de Chelly, Shiprock,...

Silver Fox at Looking for Detachment is the first to report on regretting leaving a geological/archeological item in the field.  From her account, after being literally dropped-off by helicopter at a field site: ..."I found a large pink projectile point in the middle of the drainage I was walking down, a drainage that had obviously seen some flooding in the last 1 to 5 years. The point was possibly made of Ivanhoe "chert" (more precisely opalite or silicified tuff) from the Tosawihi Quarries of northern Nevada, a large series of rock quarries made by ancient to nearly present-day native Americans..."   In following accepted archeological protocols, she left the point, intending to mark the locality on a map for later collecting by a "trained professional".  For whatever reason, the info didn't get passed along and the point was probably washed further downslope with later weather events.  [I once got a polite lecture from a friend about collecting a silicified limestone "hand tool" from a roadside site, but I was able to drive him to the site and point to the exact location, so he could relate it to his archeologist girlfriend, so no damage done.]

The next contribution comes from Egypt!  Way cool.  Selim Abdelrhman reports on the strange rocks of Wadi Elbattekh in Egypt.  From his words: "OK, Wadi Elbattekh or وادي البطيخ my translation is “Watermelon Valley” it’s a Wadi filled with strange rock shape and very soft in touch. i think the origin of this rocks is still a mystery."...




From Casey at Gioscience comes regrets of not having collected more samples (and taken more photos) of ripple-marked sandstones during at 1998 GSA Southeastern Section fieldtrip in WV, a fieldtrip that included the legendary sedimentary petrologist Bob Folk.  The ripple marks were in the Devonian Foreknobs Formation, part of the Catskill Delta.




The proprietor of GeologyMelange brings us his first geoblog post.  The subject of regret was a past visit to part of Marble Canyon in Death Valley.  Of most interest was an apparently un-mapped outcrop of deformed crinoid "hash".  There were a sufficient number of photos taken, but no measurements were taken of the size or orientation of the outcrop and not enough samples were collected.  But of even more interest were the cobbles of white marble, the origins of which were not discovered.

A photo of Christopher with a fault-breccia in Marble Canyon, just above the canyon sediments.











Ron Schott admitted not collecting enough samples from certain sites, taking enough notes, or taking enough photos.  But his greatest regret was losing his first Estwing Rock Hammer, which he was given as part of his Colgate Univ. Field camp gear.  It served him well in field camp, but when he visited Giant Mountain in the Adirondacks, the spirits of the mountain became incensed at his collection of samples of the Roaring Brook intrusion breccia.  The spirits extracted their revenge by relieving him of his beloved hammer from its improvised rope belt.  [I know the feeling.  My Dad gave me a brand new Estwing Rock Hammer when I left home to go to UTEP for grad school.  Despite having the handle wrapped with day-glow orange tape, I managed to lose it in the Eagle Mts., about a year and a half later.]

Jessica Ball (aka Tuff Cookie) has a similar story of losing a "first piece of field equipment", a little smaller, but still important.  Somewhere in the area of Sugar Hollow in the Virginia Blue Ridge Mountains, her first hand lens slipped off its lanyard.  From a separate adventure, she regrets not having kept her first pair of hiking boots, with partially-melted soles from an encounter with some of Kilauea's fresh lava flows.  I am sure that those boots would have been good for some stories.

For my contributions, there are actually two different ones. In 1979, I had a summer job in the San Juan Basin of NW New Mexico, as part of a fossil recovery project, prior to the opening of an open-pit coal mine. Outside of our project area - on the road back to the dirt "highway", there was a reddish-colored outcrop of "clinker" material, i.e., baked Cretaceous shale with plant fossils. The baking was probably courtesy of an ancient, underground coal-seam fire. After driving by this site to - and from - my "days off", I decided to stop and have a look. I regret only picking up two specimens from this site, one (pictured) with an angiosperm leaf and a stem fragment and another with a piece of a stem. WHY DIDN'T I AT LEAST FILL A BUCKET FROM THIS SITE? I will never know.


The image is labeled for use in my classes.


The other under-collected site was the previous summer, when I was in the Eagle Mountains in West Texas. While surveying the area - as part of a planned thesis project, which was never finished, in favor of another a few years, later - amid the caldera breccias and ash flow tuffs, I found a chunk of siltstone, with some tiny impact craters. I regret not even doing a rough draft of the extent of this intra-caldera siltstone. It most likely was reworked, water-deposited ash, with roughly-defined bedding planes. The surface was marked by a few tiny impact craters, suggesting bombardment by explosion debris, while the upper surface was exposed, but soft and "plastic". Looking at cross-sectional view, there was evidence of other small impacts by broken crystals/rock fragments. I often include this in lab instructions to remind students that it is possible to find sedimentary rocks inside of volcanoes. SO WHY DIDN'T I PICK UP MORE CHUNKS OF SILTSTONE?  [BTW, the place where I lost my Estwing rock hammer was a stop or two past the siltstone locality.  Hmm, is there a connection?]

[Update: A couple more attendees to the party!]

Water and Rocks...At The Same Time reports on the discovery of a chevron fold in an outcrop of the Dolgeville Fault on a tributary of the Mohawk River, near Dolgeville, NY.  The photo at left shows a portion of the fold.  Several members of the field trip party picked up folded portions of (presumed siltstone), but Roy didn't want to add anymore clutter to the crowded van (be there, done that on a crowded field trip bus, it is hard to keep samples organized and under control).  This was his 2nd chevron fold, the first he donated to his alma mater, SUNY Oneonta.  Roy, you have my permission to collect the next chevron fold for yourself.

Dr. Ian at Hypo-center reports on some important items ALMOST LOST during field work in Lukmanier Pass region of Ticino, Switzerland years ago.  After picking up a fair-sized sample of gneiss: ..."I was crossing a boulder field and noticed an interesting looking exposure up a steep face to my right. I put my notebook down on a rock, placed my map case on top of it, and my gneiss sample on that to stop it blowing away. I then headed up to the steep outcrop with my compass-clinometer thinking I could easily remember a couple of readings and rock details and return to record the information in my notebook."...  After climbing upwards to check out more interesting metamorphics and record several more structural readings, he turned around to re-orient himself and return to collect his sample, notebook, and map case, when he realized - "Just damn! - all them boulders look the same!" (or something like that).  More from Ian:  ..."After an hour a mild panic started to set in. Had I just lost three weeks work down to my own stupidity? Since I knew that they had to be in the boulder field somewhere,..."  He searched for two more hours.  At the point of almost giving up hope, he decided to do two more passes through the boulder field, then he realized that the items of interest were a mere 10 meters away from him.  But a sad postcript follows this reunification of geologist and field equipment...  ..."After my degree, I went to Cardiff to do a Ph.D. and I told the metamorphic petrology lecturer about the wonderful metamorphic rocks at Lukmanierpass, including hornblende garbenschiefer and kyanite schists...I showed him the box of my rock samples that I had collected there. He asked if he could hang on to them for a while and I agreed. With the passing of my Ph.D. I completely forgot that I had lent him the rock samples. I moved on to Keele, and he moved on from Cardiff."  So the location of the box of rocks is a mystery.

Well, us Geologists and our stories of "the ones that got away".  Maybe some younger folks will learn something from our travails, lost samples, unphotographed localities, lost equipment, and regrets.