Down Memory Lane, Lurching I Go, Again ... Part 1

 While posting about the context of my past for the last few days, I am sporadically running across scanned 35 mm slides from my time in El Paso (1977 - 1991).  That time included my "truncated" (1978 - 1980) Thesis Project in the Eagle Mts.  As the years trundle by, this year is the 42 anniversary of that conse-quential summer of 1978.  

In the upcoming "My Background - Part 3" I have several links to my postings about the 10 weeks I spent in the Eagle Mts in 1978 and sporadic visits I made in the following two years.  Though I didn't finish my portion of the project, the time and adventures there made life-long memories, even for some of the things un-photographed and a few regrets.  [More links will be in future posts.]

Figure 1.  East Mill, Eagle Mts., Texas 

[I have been engaging in photography since early 1975, initially with 35 mm film photography until 2002, then digital after that.  This 1978 slide (looking roughly East) is one of my top-five favorites.  Some of the far ridges and ranges are probably 30 miles away.  With a little map-review, I could name most of them.  The moderate hill in the middle-ground (behind the windmill frame) is probably composed of Cretaceous sedimentary rocks.  Beyond the hill is "Eagle Flat".] 

It began in the Spring of 1978.  In preparation of the planned summertime mapping of the Eagle Mts., in quadrants for four Master's Theses, my Spring courses included a semester-long Seminar on Volcanic Rocks and a separate course on Volcanogenic Uranium.

Spring field trips included; 1) Visiting a uranium mine at Sierra Peña Blanca, Chihuahua, Mexico; 2) The nearby Northern Quitman Mts., also in Hudspeth County, Texas; and 3) The Valles Caldera, near Los Alamos, NM.

We were studying calderas and their associated pyroclastic volcanic rocks.  And my quadrant included the volcanics of the SE portion of the Eagle Mts.  My field-partner Dan did not have a 4x4 as I did, so in exchange for his helping me with my fieldwork in the SE quadrant, I agreed to chauffeur him around in his SW quadrant.  Mutual study of both quadrants, we hoped, would lead to a greater understanding of the mountains and their geologic history.

The Northern Quitman Mountains and the Eagle Mountains are just two of the numerous, large volcanic centers that comprise the Trans-Pecos Volcanic Field and part of the regional Late Paleogene "Great Ignimbrite Flareup", that was active between 40 and 25 m.y. ago.  

The calderas close to the Rio Grande variously erupted upon existing Laramide-aged thrust sheets of the "Chihuahua Tectonic Belt".  And most eruptive centers within the region were later modified by Neogene Basin and Range extension and faulting.

Once we moved into the mountains, we spent a day or two exploring in portions of the NE quadrant (to be mapped by Mike, while the NW quadrant was to be mapped by Bob) and just "getting a feel for the place".  Upon entering the mountains from the east (leaving the adjacent Eagle Flat area, and its Creosote Bush/Mesquite Biome), we noticed that there were valley grasslands with scattered Scrub Oaks, Juniper, and Pine trees.  Indeed, on the first day in the mountains, I lost my right-side mirror and radio antenna to a pine limb.  One of the east-facing valleys even had some muscadine (wild grape) vines.

As time passed, we would come to further observe that the eastern slopes and valleys of the mountains tend to be wetter than the west side.  One reason for this is that the eastern facing slopes and valleys get the "cooler" morning sun, allowing soil-moisture to be retained in contrast to the western slopes and the "hotter" afternoon sun.  [On the west side of the mountains, I don't recall seeing valley and slope grasslands (with scattered trees) similar to those shown in Figure 1 at East Mill.]  

I observed (some years later) this eastside/westside diversity of "microclimates" in the Organ Mountains of southern New Mexico.  Because of varying elevations and orientations within mountains (especially in the desert), mountains are known as "islands of diversity".  [Slope and valley orientations are important in regard to length and intensity of "sunlight hours", as suggested above.  This influences soil development, plant diversity, and plant density.]

When Dan and I moved to the SE quadrant, we chose to be close to a landmark and emergency water, so we camped at East Mill (above).  Later, when working in Dan's SW quadrant, we camped at an unnamed mill on the southwestern slopes of the mountains and at another site on the broad alluvial fans extending out from the mountains. 

[More Eagle Mts. photos planned for future posts and the References section with links, later.]