Monahans Sand Dunes

Saturday, Nov 13, 2010, 2 PM.  Sabkha and I leave for Monahans Sand Dunes State Park, about 50 miles down the road.  Over the edge of the Llano Estacado.  We parked at the surreal, 70s picnic area and, with the help of my Silva compass, we head due north under the watchful eye of a park ranger/garbage can checker.  North, north, north.  Trying to stick to the sand.  Where the sand dunes are covered with shin-high scrub oak, it's tougher going. 

 

 Spider hole?  Why throw the sand in a circle?

North.  Soon the dunes change from wide open, mostly sand, to mostly covered.  We saw a variety of interesting things.  Sand globules that looked like they might be fulgurites, but where probably cemented animal pee spots.  Sabkha had an absolute blast, freedom, freedom.  In some low dune valleys we found outcrop-looking carbonate rock, I think it is caliche formed in place.  Caliche would be mostly calcium carbonate, aka limestone, formed typically at shallow depth.  Either by water carrying minerals downward, then depositing, or water carrying minerals upward, then evaporating.  In this case I think evaporation is the culprit. 

 

Sea of sand

North we hiked.  Every ten minutes I took out the Silva to find we were headed off course.  Trying to stay on the sand -- it's hard to walk in a straight line.  Finally, we were at the edge of the dunes.  To the northeast there was a line, dune to desert scrub transition, a line of the sand.  Ahead I saw a big silver tank, probably an oil tank, and we set a course toward it.  At the edge of the sand we stopped; we'd been hiking north about an hour and a half, with many stops.  The straight line distance covered was about 1.5 miles, I found later on Google Earth. 

 

 Caliche in a depression

Going back south.  South.  On the way north we had gone through a wide stretch of thick ground oaks.  To avoid these we stayed a bit west.  I found the setting sun to be close to SW, but I don't have my Silva set to the magnetic declination of this place, probably set to Utah in 2004.  UA field camp TA.  On the way back, we saw different things.  A few signs for well heads, and a metal pipeline.  In the distance to the east I saw a windmill sticking up above the sand.  Suddenly I heard a thump, a snort, a grunt, and a large black pig was off, running away over the hill, and Sabkha behind it.  Several shocks later and Sabkha wheeled around and came back to me.  No more pigs were spotted. 

 

Where is the car...?

Atop a dune, a bit lost, I could see the highway and the train in the distance to the south.  To the southwest I saw a single figure on a high, clear dune.  We dropped into a valley, looking meandering like a water-carved valley, and paved with blue caliche at the bottom.  The caliche had little bits of rock stuck in it; rather unusual in marine limestone, so again evidence this was formed in situ.  Sabkha was stopping every fifty feet to lick her front paws.  I checked for goat heads and found none; I think she was suffered from SPA (sand paw abrasion).  Through a sea of sand, right near the parking area is the sandiest, less than 10% vegetated.  Pop, over the hill, romp romp romp, down the hill to the Subaru. 

 We saw a number of mushrooms like this one.  They were in groups.

Back to Midland on I-20, setting sun directly behind, blip, gone, dark dark darker, speed limit from 80 to 70 to 65 mph.  Night. 

Fuel.  Pump pump pump click.  25 mpg.  93,000 miles.  $2.629.  Sabkha sleepy.