Field Mapping in Taos, New Mexico
Back in 2012 when I was doing field work in Taos, New Mexico, I learned so much about recording data, processing it all, and presenting either a visual or written representation of the processes that sculpted the landscape. I haven’t been back since but I hope to very soon! The remoteness, geological features, and beautiful Colorado River really make Taos a beautiful place to be! The group of students I was with came from New York, Texas, Mississippi, and Florida and for weeks we studied magnetic anomalies, which were significant in describing an enormous batholith, progression and regression of water levels on what used to be a shoreline, and metamorphism.
The first project we tackled was an interesting one. There were no rock exposures anywhere in site, so it’s safe to say we were all a little confused. No exposed rock means nothing to map right? Wrong! The only tools we were equipped with was a map, gps, and a magnetometer. We walked in a pattern that resembled a lowercase t. Every few thousand feet we placed the magnometer on the ground and recorded the gps location and the magnetic field units(gauss).
After being out there for a few hours we found a cow skull and some interesting readings from the magnetometer. The whole time we were being briefed on what we should expect our readings to be as a result of Earth’s magnetic field. But our readings were quite different. Turns out a batholith buried deep beneath our feet was throwing off all our measurements. The many hours and directions we walked were able to tell us where the outer limits of the batholith was, and because so we were able to calculate the square footage of it. It was some of the most unique mapping I had done yet.
Next was one of the most complex landscapes we studied. We were just dropped off on the side of the highway and told record what you see. We went out there for 3 days straight from sunrise to sunset with a map, hammer, brunton compass and our field notebook.
I saw chert beds, sandstone beds, mudstone beds, completely overturned limestone beds. While I was eating lunch one day I was digging where I was sitting and found a huge almost optical calcite bed! There were countless bivalve, mullosk, and gastropod fossils scattered all in the limestone beds and down the ravines. I even found some crinoid fossils, these are my favorite fossils by the way.
After our mapping was complete we had to interpret what we saw by drawing a representation of the beds and faults we recorded and wrote a geological timeline of processes that created the landscape. It was truly fascinating to see the facies change of what once used to be a shoreline that had gone through multiple sea level rises and falls!
Lastly we mapped a metamorphic belt deep in the mountains right outside of Taos. Most of the mapping was done in a deep ravine which could have flooded immediately if there were a flash flood. Kinda tripped me out being down there, but man did we see some really neat metamorphism. We saw some meta-conglomerates which had elongated clasts due to stresses in the east west direction. All of the rocks in the matrix looked like footballs or Stewie’s, from family guy’s, head.
Something I’ll never forget were the garnet and staurolite schists. They had so much sheen due to its mica concentration and the crystals of garnet and staurolite were so well defined. Thinking about it now, I’m upset I didn’t collect more samples. Being in this ravine helped us get a feel for the types of stresses these rocks had been under for the last hundreds of thousands of years. And this helped us paint a picture of how the mountains surrounding the area were erected.
One of our goals here at Geology Rocks! and Minerals are to eventually take people out on the research driven field trips so they can see all the beauty this earth has and to understand and visualize the processes that have gone on to create what we see and continue to go on to this day. The trip to Taos changed my life and opened my eyes, and I hope to do this for others too!
- Kasey V