This earthcache covers
two geologic formations here in the Turlock area. The first is a
strange, temporary sand formation, the second being a spot where
sedimentary layers from the formation of the Central Valley can be
seen.
John Muir once
wrote of how the temporary sand formations in the Turlock area
allowed him to observe serveral of the local animals' tracks. He
said, upon finishing his observations "The mouse, lizard, and
grasshopper sing together on the Turlock sands..." What I mean by
temporary formations refers to how they are formed. They are caused
because of the relativly high temperatures here, even in the
winter. What happens is the soil in the area does not allow the
sunlight to penetrate deeply into the soil and all the heat energy
upper layers. This causes the already loose upper layers of dirt to
dry out even more than the rest of the soil and seperate from the
still moist dirt underneath it. The end result of this is a thin,
almost invisible layer of loose sand that covers the field around
Turlock. When high winds kick up, the sand becomes part of the
area's smog problem, with nasty air
quality reprucussions. And in Muir's word, "These lesson
learned in turlock sands will stay with me
forever."
The second feature
to be seen at this location is sedimentary layers from the very
earliest days of the Central Valley. These layers were formed
because of what this area was before it was the great valley it is
now. At one time this whole area was underwater as part of the
young pacific ocean. At some time between 200 milion years ago and
150 million years ago the coastal ranges to the west started to get
pushed up by tectonic action, cutting off this area and forming an
inland sea. Eventally this sea was completely cut off from the
Pacific, so it formed rivers through the new western mountains and
drained back into the pacific. Since the bottom of the sea was
flat, this draining caused the new valley to be very flat as well.
The area is also rich with fossil deposits, mainly fish and
shellfish. Their bodies became intombed in the mud at the bottom of
the sea when they died. The mud and the bodies of the animal
hardened into limestone and shale when the sea drained, forming the
bedrock of the Central Valley today. The bedrock of the central
valley is limestone and sandstone, both relatively soft
rocks.
To get credit for
this earthcache email me the answers to the following
questions:
1. The name and GC code of this earthcache.
2. The number of people in your group.
3. Are any of the thin sands visible?
4. Does the formation appear to be sandstone or
limestone?
As always have fun and Leave No trace! Congrats to mulvaney on
the FTF!
