The Algodones Sand Dunes of the Imperial Sand Dunes
Recreational Area are the largest sand dunes in California. This
dune system extends for more than 45 miles along the eastern edge
of the Imperial Valley in a band averaging six miles in width in a
northwest-southeast
line that correlates to the prevailing northerly and westerly wind
directions. The dune system is divided into many different
areas. The wilderness area lies divided into two distinct zones:
the primary dunes on the west side and the secondary dunes on the
east. The former are taller and larger, and composed of noticeably
coarse
sand. The latter are
smaller, made up of finer sands that are periodically shifted
even farther east by prevailing winds.
Millions of years ago the earth's crust
shifted along the San Andreas Fault, the coastal mountains were
pushed up, cutting off the moisture-laden air coming from the
ocean. At the same time, the interior plains of Southern California
began to drop, forming a basin known as the Salton Sink or
Graben;
gradually, the region dried.
The area that the Colorado River flowed
through in this region was so flat that the course of the river
varied, being periodically diverted in one direction or another by
flood deposits. At times the river flooded the Salton Sink forming
a freshwater lake called Lake Cahuilla.
It’s believed that the dunes formed from windblown
beach sands of Lake Cahuilla. The prevailing westerly and
northwesterly winds carried the sand eastward from the old
lakeshore to their present location. This process continues today.
Prevailing winds cause the dunes to migrate southeast at the rate
of approximately one foot per year. The primary force shaping the
dunes is wind, and by understanding the relationship of wind to
sand, you can learn to "read" the dunes. Dunes are generally
oriented at right angles to the wind. Since the wind here generally
blows west to east, the dune crests generally follow a north-south
orientation.
"What a desolate
place this is."
-
C-3PO 
DID YOU KNOW?
The dunes were used to film parts of Road to Zanzibar,
Stargate, Resident Evil: Extinction and the Tatooine
scenes in the Star Wars series.
Types of
Dunes Classification Triangle -Interactive
TO LOG THIS
CACHE:
1) Classify the dunes you see from this location using the
“Types of Dunes Classification
Triangle”.
2) When was this area of the
park your standing on dedicated?
To log this cache
e-mail me the
answers
HERE.
Sources: