Along the road to the group campsites at Indian Cove
Campground there are a few areas for day parking that get you
very close to the features.
During the last ice age, which peaked about 18,000 years ago,
the area around Joshua Tree National Park had a cooler and wetter
climate. In this climate, more plants were able to survive in the
area creating and stabilizing a thicker soil profile than exists
today. The soils did not cover the inselbergs
(
See inselberg earthcache) common in the park, but only covered
their base.
In the upper layer of soil, the byproducts of the plants and
microbes generate acids that break down the minerals in granite
faster than above and below the upper soil layer. The northern side
of the rocks is also slightly shadier and thus remains moist longer
than the sunnier sides of the rocks. The result is a roughly
horizontal indentation (notch) around the inselbergs that is
slightly more pronounced on the northern side.
A second way to identify the location of the ancient soils is
the change in coloration of the granite. The soils above the
ancient soils have been exposed to the air and formed a desert
varnish (the darker coloration) while the soils below did not.
As the ice age ended, the area around Joshua Tree became dryer
and hotter. Fewer plants could survive, exposing the ancient soil
to erosion. These ancient soils have been transported away lowering
the surface of region and leaving the notches that marked the
elevation of ancient soil above the current ground elevation.
Logging requirements:
Send me a note with :
- The text "GC1BJ44 Evidence of Ancient Soil" on the first
line
- The number of people in your group.
- At the coordinates, how many feet of soil has been eroded
?
- At the secondary coordinates (N34 05.868 W116 09.910), look
around the inselberg and see if the northern side has a more
pronounced notch than the southern side.
The following sources were used to generate this
cache:
- Trent, D.D. & Richard W.
Hazlett, Joshua Tree National Park Geology, Joshua Tree National
Park Association, 2002
Placement approved by the
Joshua Tree National Park