Sunday, May 20, 2018

Geo-Learning

It goes on daily.  

Or at least I try to learn something daily, whether it be Geology, Biology, Ecology, Environmental Science, Photography, Botany, History,...

(Whisper, whisper,...this is to partially-offset what has been forgotten over the years.)

Yesterday, it was the Vulcanology-related use of "boca" (Spanish for "mouth").  My first exposure to the term was at Capulin Volcano in northeastern New Mexico in the summer of 2015.

There is a good resource available, "High Plains of Northeastern New Mexico: A Guide to Geology and Culture", New Mexico Bureau Geology & Mineral Resources; Scenic Trip Series, Number 19.  (2005) Muelhberger, Muehlberger, and Price.

(Screenshot below from this source.)


High plains of northeastern New Mexico : a guide to geology and culture

Originally, I purchased this book while planning a 2009 summer vacation for my first wife, son, and me.  After visiting relatives in NW Oklahoma, the plan was to go a bit "beyond there", as finances and time permitted.

But "as we make our plans, life happens".  As the summer of 2009 approached, my son in-law had a job interview in NYC and my daughter didn't want to be left alone at home with a 3 month-old son.  So she planned to drive her SUV with my wife and I rented a Plymouth PT Cruiser for my son and I to caravan to Oklahoma and back.  [The "NYC gig" lasted for about two years, deemed to be good for a short bit, but too expensive.  So they came back to Georgia.]

On the 2009 journey, as 3 month-old Ben was not used to be in a car seat for long distances, he screamed incessantly, frazzling my daughter, the new Mom.  Frequent stops were necessary, as she didn't know if he was hungry, wet, dirty, or just dissatisfied with the car seat with his vocal protestations.  We got to Oklahoma to see the inlaws and so they could meet their first great-grandchild.

Not wanting to be on the road for longer than needed, the NM trip was nixed.  And my absorption of the book was no longer needed.

As we planned to go by Dallas on the way back to see more relatives and frequent "Ben stops" were necessary, once we got to I-35 south of Oklahoma City, my son and I were able to take the short back road (US Hwy 77) through the Arbuckle Mts. and I did get some "geo-photos" and a few rock samples (pictures in a later post), before we hooked back up via cellphone.

After returning to Georgia, the book went back on the shelf until the tumultuous summer of 2015.  In the interim, my only thought about the discarded plans were "I want to visit Capulin Volcano, someday".

(Story to be continued on "Itinerent Geologist", soon.)

Wednesday, March 21, 2018

Memory Lane Visit

Lurching down Memory Lane, when one memory triggers another...(don't know why sometimes.)
Twenty years ago, while still working for the Georgia Geologic Survey, we were redirected to complete a USGS-funded stream sediment study across the southernmost tier of Georgia counties, from the Alabama line to the Atlantic Coast, perhaps comprising 20% of Georgia's 159 counties.
If memory serves me correctly, it was to study the trace minerals, i.e., minerals which contained rare elements, within the stream sediments we collected. There were EPD employees from various branches. (Though it was during January and February, it was a welcome break from the routine for a few weeks.)
The particular memory was of one of my GGS coworkers being paired up with a Biologist from another EPD branch. Now as I have been a beer can collector, as well as a general packrat for decades, I sometimes pick up old stuff while in the field. Nothing unusual there, though I think this particular coworker didn't have any "side hobbies" as I do and I gathered that he "looked down his nose" at my "low brow" collecting interests.
Perhaps as some sort of karmic payback, my coworker was paired up with a female Biologist that had an interesting "side hobby". She like to gather fresh (or relatively fresh) roadkill, take her treasures home, boil them down to retrieve the bones and reassemble the skeletons.
I was using an EPD pickup truck with a hinged bed-cover, while my coworker was using some sort of EPD passenger car. This is important, as while my sediment samples (and any old beer cans and such) went into the bed of the pickup, the Biologist's dead animals went into the trunk of the car (into a Styrofoam cooler, which isn't air-tight). Over the course of each week, she picked up several dead critters that added their "aromas" to the ambiance of the car, resulting in the need to keep the windows open.
Each morning, we gathered at the motel as I gave them their maps and suggested collecting locales for the day (on a grid pattern). When this coworker complained about his field partner's collecting habits, I couldn't help but ask him which he preferred, my old rusty beer cans or her dead animals, which triggered an epiphany for him, as he gave me a look which said: "Do you even have to ask?". (I was no longer the craziest person he knew. I think he did manage to get her assigned to another vehicle for the last week or so.)

Tuesday, March 6, 2018

Xenoliths

Aside from being a nifty word for Scrabble, "Xenolith" is an important component of the concepts of "Inclusions" and "Relative Age Dating".

For a quick review, a Xenolith is a piece of pre-existing rock that "falls" into a body of magma in which the temperatures are not hugh enough to assimilate the "foreign rock".  As the xenolith is an already-solidified piece of rock, it is older that the "host magma" (or lava) into which it falls.  Thus, within the xenolith/host rock relationship, the inclusion (xenolith) is always older than the host rock.

My best luck at collecting Xenoliths has been in Kilbournes Hole, New Mexico and the Eagle Mts., Texas (decades ago) and the back lot of a granite monument cutting business, west of Elberton, GA (below and next post).


In this particular Franklin Mts. outcrop (below), there are at least two sets of Xenoliths, the black basalt/disbase blocks and the greenish-gray contact-metamorphosed limestone, both of which "fell" into the Proterozoic Red Bluff Granite magma. 
 
This second photo, immediately west and uphill of the above, shows remnants of a larger Castner Marble (limestone) xenolith.

This photo is of a xenolith in the East Quarry area of Stone Mt., Dekalb County, Georgia.
 This particular xenolith is from the Elberton Granite.  [This image was "squared-off" - using Photoshop - for education purposes.]
In the case of the Mantle Xenoliths erupted in "volcanic bombs" at Kilbournes Hole, New Mexico, the ultramafic fragments were carried upward by the basaltic magma and erupted in a "Maar Volcano" setting.

Previous bloggings about the subject:

Kilbournes Hole, NM 

What a Geologist Sees - Part 3

What a Geologist Sees - Part 13

What a Geologist Sees - Part 14

Boulder xenolith, Eagle Mts., TX  


Saturday, December 30, 2017

Life Changes

As life continues to evolve,...

Got married a few days ago.  Moving about 25 miles to my bride's existing home, including books, rocks, and such.  Job changes.

2018 New Year's Resolutions will give a new impetus to resume blogging.

Wednesday, September 20, 2017

Will be back soon.

I am not doing a mental "walkabout", just busy with daily tasks, including cleaning up remaining debris from Irma's visit last week.  Nothing major, though we were without electricity for almost three days.

Saturday, August 12, 2017

Between Posts, a Brief Hiatus

When I resumed blogging on a regular basis, my intent was to blog everyday.  But life intervenes.  Nothing bad, just a social life and class preparation.

Friday, August 11, 2017

Kilbournes Hole, Potrillo Volcanic Field

It has been decades since I visited Kilbournes Hole, in southern Doña Ana County, New Mexico.  It and its companion Hunts Hole (less-developed and to the East) are both defined as Quaternary "Maar" volcanoes.  These two craters are within the southern part of the Potrillo Volcanic Field.  Maar volcanoes form when rising magma encounters surface water or a shallow aquifer, resulting in a series of phreatic (steam explosions), which "blow a hole in the ground".

In this case, a southwest-extending "tongue" of the existing Afton Basalts overlay the site of the steam explosions.  Without the pre-existing basalt flows, the rim of the maar would likely have been more subtle, as is the rim of Hunts Hole.  The surface "host" consists of lightly-consolidated Quaternary basin and fluvial clastics, e.g, Camp Rice Fm. 

The basalt flows in the middle ground of the photo are the Quaternary Afton Basalts, slightly older than the previously discussed Aden Basalts.

Unusual for basaltic eruptions, the phreatic explosions pulverized the lavas and with the help of prevailing winds, deposited cross-bedded, Base Surge Ash beds, primarily on the east side of the maar.   

Other "Geologic Toys" scattered about the exterior of Kilbournes Hole are numerous "Volcanic Bombs", many containing Mantle Xenoliths, primarily of Olivine and Enstatite.  This particular Xenolith is about 5 - 6 inches across the largest dimension.


[I may add some additional notes, later.]