Guadalupe Mountains and Capitan Reef

Picture the map of Texas.  You know the part that sticks out to the west, ending in El Paso, with a long straight east-west border between the north side of that part of Texas and the southeast side of New Mexico, right below Carlsbad.  That is where the Guadalupe Mountains are, and Carlsbad Caverns are part of that geology.  A major formation comprising the mountains is the Capitan Reef, the largest marine fossil limestone reef known in the world.  The southwest head of it is known as El Capitan.

This formation is one end of a gigantic U-shaped limestone reef that extends up past Carlsbad, curves around back into Texas, and continues for over a hundred miles.  Much of the formation is still buried under subsequent layers of sedimentary rock, but it is exposed at the surface in several named mountain regions.  Carlsbad caverns are carved (well, actually dissolved) out of this same limestone.  It is one of the most significant and interesting geological formations in the world.

As you drive south from Carlsbad toward El Capitan you come first to McKittrick Canyon, which has a small visitor center and hiking trail up into the canyon.  Tyler and Paula walked a short way up into it.  White limestone everywhere.  You can Google it and learn about the rich diversity of plant and animal life in this unexpected oasis in the middle of the vast American western desert.

 

White Sands, NM

On Saturday, Nov 14, we drove down to White Sands.  Despite the fact that Tyler and Paula both grew up in the Texas Panhandle (Hereford and Levelland, respectively) and had visited Carlsbad Caverns several times, neither had been to White Sands.  It's even more interesting now that Tyler has read up on some geology.  The "sand" is not the usual quartz sand (which is crystalline silicon dioxide, from which ordinary glass is made).  It is composed of small crystals of the mineral selenite, which is the crystalline form of gypsum, or hydrated calcium sulfate:  CaSO4*H2O.  You can read on the White Sands website how it is formed and how it collects into dunes.  One consequence of the different chemical composition is that this sand is very much softer than quartz sand.  I.e., quartz is quite abrasive, and will successfully scratch a wide variety of other materials, including ordinary car windshield glass and paint coatings.  White selenite sand will not scratch much.  Of course, you still don't want it in your socks!

Valley of Fires lava flow, Carrizozo NM

Last week Tyler, Paula, and Paula's two sisters from San Antonio rented a cabin in Ruidoso, NM.  The weather was lovely- cool, clear, and crisp, warming into the low 60s during the day.  One day we drove over to Carrizozo, NM, to view the Valley of Fires Recreation Area.  It's a fascinating area of lava flow from about 5000 years ago, averaging 45 feet deep,  and up to 160 ft deep at its deepest.  It originated from a volcanic rift zone northwest of Carrizozo and flowed down a valley a few miles wide and 45 miles long.  The lava is black basalt, similar to what is found in Hawaii, but it results from a rift volcano - - ie, an upwelling of lava where the earth's crust is spreading or pulling apart, as it has been in NM in recent geological history.  In contrast, the Hawaiian volcanos is due to a local hot spot under the crust.

There is much beauty among the lava, including this one:

Here are some more pictures of the lava and its flora: