Talus
slopes form as pieces of rock fall away from the bedrock of the
cliff or hillside above. Usually the main mechanism that splits off
these pieces of rock is ice or frost heaving. Water gets into small
cracks and freezes, expanding and pushing the crack wider.
Eventually the rock is wedged off falling down onto the pile of
rocks below.
These rocks pile up to a maximum angle called the angle of
repose, the same term used to describe the maximum angle a sand
dune will achieve. This angle is dependant upon the size of the
grains.
The term scree slopes is also used to describe these landforms,
but typically scree is used for rocks that are smaller than about 1
foot.
The Tokopah valley was filled with a Glacier during the Tioga
(14-25 thousand years ago) and Younger Tahoe (42-50 thousand years
ago) glaciations, and at least one pre-Tahoe glaciation. The
glaciers that moved through the valley carved it out into a typical
glacial U shape (see Tokopah Glacial Valley Geomorphology). The
glaciers eroded portions of the valley into sheer cliffs. However
after the supporting ice receded, ice heaving began taking its toll
on the cliffs creating this talus slope.
Logging requirements:
Send me a note with :
- The text "GC2XJXF Tokopah Talus Slope" on the first line
- The number of people in your group (put in the log as
well).
- What is the size range of the rocks that make up the talus
slope?
- What features of the rocks that make up the talus slope show
that they have been wedged off the surrounding mountains and
fractured by ice?
Scree - Wikipedia
http://en.wikipedia.org/wiki/Scree