This location is adjacent to the unpaved section of Soda
Lake Road. While easy for all vehicles in dry weather, wet
weather may make the road impassable. No off road vehicle
travel is allowed to reach the site. Collection of plants,
rocks, or any artifacts is prohibited. If turning around, stay
within the road bed and do not go into the field. Practice
Leave No
Trace principles.
About 2.5 million yeas ago, movement along the San Andreas Fault
created a geologic basin that began to be filled with alluvial
sediment from the newly formed Temblor Range to the east and the
surround coastal ranges. These initial gravels and sands that
filled the basin are called the Pasa Robles gravels since they have
not been consolidated into a rock. Later continued movement on the
San Andreas turned the isolated the basin (see
Soda Lake EarthCache).
Currently, sediments are still being eroded from the surrounding
hills and deposited on the plain. Larger grain sizes (sands and
gravels) are deposited at the base of the hills, while smaller
grain sizes (silts and clays) are deposited in center portion of
the basin. Periodic high intensity rainfall events rework the
sediments of the plain and transport them further down toward Soda
Lake.
Running water is a powerful agent of erosion. Water erodes one
of three ways:
- Physical movement of individual particles;
- Physical striking of the moving particles against non-moving
particles; and
- Chemical interaction with the surrounding material.
The physical aspects of water’s erosional potential increases as
the volume and velocity of the water increases. Thus as water is
concentrated into the same area and as it moves faster, the more
erosion takes place.
Erosion in caused by moving water takes place in three
areas:
- The sides of the channel, lateral erosion;
- The bottom of the channel, downward erosion; and
- At the start of the channel, headward erosion.
This gullies form where precipitation runoff was concentrated
along the old road bed of Soda Lake Road. The road was moved to its
current rout in the 1960s. It is likely that the lack of vegetation
along the old roadway made it easy for the erosion to begin.
Logging requirements:
Send me a note with :
- The text "GC1VKDD The Soda Lake Road Once" on the first
line
- The number of people in your group.
- What direction of erosion is being prevented at this location
and why?
- Is there evidence that erosion in the other directions is
occurring?
- In your opinion what ways is water eroding the gully you
see?
The following sources were used to generate this
cache:
- Judith Hildinger, Carrizo Plain Natural Area,
Two Self-Guided Geologic Auto Tours, 1995.
-
http://geography.about.com/od/physicalgeography/a/erosion.htm
- NPS website,
http://3dparks.wr.usgs.gov/carrizo/html/b014.htm
Placement approved by the Carrizo Plains National Monument