There
are a few parking spaces near Skull Rock, but it is a popular
location, so it may be hard to actually find one.
Tafoni are one of those features that still needs a definitive
explanation of their formation. Some are large and spaced apart
like those at Skull Rock. While others appear to be like honeycombs
on the side of granite faces. At Joshua Tree, tafoni are found only
on the granites. The gneisses of the park generally erode much more
easily due to their layered minerals.
One theory for the formation of tafoni begins with the thicker
soils that covered the region during the last ice age. Some granite
surfaces were in direct contact with wet acidic soils that weakened
the structure of the rock, much like the soil notches (Evidence
of Ancient Soil). Some areas may have been slightly more acidic
than others, creating uneven erosion across the buried rock face.
After the soils had been eroded away, these weaker areas eroded
more quickly. Once a slight depression formed, these shaded areas
remained wetter longer than the portion of the rock face that stuck
out. With more water, erosion continued at a faster rate than the
dryer areas enlarging the depressions forming the tafoni.
Logging requirements:
Send me a note with the answers to the following questions:
- Post the coordinates and pictures of other tafoni within the
park.
- Since shadier areas should create larger tafoni, find some
tafoni facing north and compare it with some facing south. E-mail
your findings to me.
Please Note:
1. You must answer all the questions in your email to me and post
all picture(s) with your log.
2. Your logging this cache and sending me the email should happen
at around the same time.
3. Begin your email with the name and geocaching code of this
Earthcache, your name(s), and the number of people in your
group.
Failure to comply with the above will result in
your log being deleted!
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