61. Big Bend Vistas: A Geological Exploration of the Big Bend by William MacLeod
published: 2002
format: 247 page paperback
acquired: 2005 from a store within Big Bend National Park
read: Nov 25 – Dec 2
time reading: 11 hr 51 min, 3.0 min/page
rating: 3½

This area is geologically bewildering. The big picture geology is this is where the Rocky Mountains and Appalachian Mountains (well, Oachita Mountains really), come together. Don't look at a map, because the Ouachita mountains disappear underground in eastern Oklahoma. The old buried mountain range continues underground to the west where it zigzags through Texas and then suddenly pops up in Marathon, Texas as an early Paleozoic window, known geologically as the Marathon Dome, and forming the edge of Big Bend country. These rocks are massively folded, and twisted and contorted (like parts of the Appalachians). Next they were buried by a thick section of much younger and flatter Permian and then Cretaceous rocks. Then about 60 million years ago came the early Rocky Mountains (not really the ones you see today) lifting everything up. After this, some 40 million years ago, came a series of volcanic stuff - molten rock flowed everywhere - between layers, cutting through in vertical walls (dikes), out on the surface creating volcanic cones, spreading ash and lava everywhere. This happened along with a lot of what is called Basin and Range faulting. Then it all went quiet and erosion took over for 30 million years. That's the simple story 😉 (you don't need MacLeod's book for this).

Driving through it over the Thanksgiving Break, knowing everything above, I could look around and have no clue what was going on. This book, a roadside geology, is crazy detailed, but it laid it all out for me, and answered a lot of my questions. The geology here is far far more complex than I realized. But geologists have actually worked a heck of a lot of this out.

I couldn't find much on William MacLeod other than a very brief obituary written by his son, who apparently worked for the Marfa paper that published it. MacLeod is educated in Scotland, but was not a professor, just a geologist who found the area interesting, lived there for many years and read everything he could. I appreciated in his brief intro where he says, "I have read most of the material published on the geology of the Big Bend in the last 120 years". That means something. The text reads as if like he's driving and you're a passenger in the car. At each point he direct you by saying "at 9:00 o'clock is...", which means you have to constantly figure out which way the car is facing, since that's 12:00 o'clock. The maps are beautiful and he pretty much covers every single outcrop along his drive, as well as what you can see from several vistas (requiring a lot of clock-face directions).

Recommended to those interested.

2019
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