Cache Creek EC (YGR1401) EarthCache
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Cache Creek is an 87-mile-long stream in Lake, Colusa and Yolo counties,
The Cache Creek basin is relatively young in regards to its geologic history. Various geologic processes are responsible for the development of the Cache Creek basin. It is geographically located near a dynamic tectonic boundary, which causes a variety of rock types to be exposed in the bedrock geology. Rocks known as the “Franciscan Complex” (Cretaceous and Jurassic sandstone, igneous, sedimentary, and metamorphic rock with smaller amounts of shale, chert, limestone, and conglomerate) and the “Great Valley Sequence” (layers of shale and sandstone up to six miles thick) dominate the area. Tectonic uplift, folding, and faulting have been the most recent events in Cache Creek’s geologic history. The Blue Ridge Mountains on the west and the Capay Hills on the east borders of Capay Valley were created by recent thrust fault activity. This thrust has shifted the direction of Cache Creek from a path that went east toward the Sacramento Valley, to its present course which heads through Capay Valley to the southeast. The channels of Cache Creek that wind through the Capay Valley display characteristics of a channel pattern that is in transition from a meandering to a braided type of channel. Typical streams that have the same pattern usually have large sediment loads, with a lot of gravel-sized particles. They also are usually much wider and shallower. These types of channels are usually unstable with chute cutoffs, meander shifts, and streambank erosion typically occurring. Sediment erosion, transport, and deposition change the morphology of the stream path in response to natural changes in stream flow and how much sediment is present. A gravel bar helps to control the channel pattern and shape the geomorphic features of the stream as it passes through the Capay Valley. The above information was found in a PDF document entitled: Cache Creek Geomorphology: Watershed-Based Assessment of Hydrologic and Geomorphic Conditions in Cache Creek through Capay Valley, prepared for the Yolo County Resource Conservation District Kamman Hydrology & Engineering, Inc. 7 Mt. Lassen Drive, Suite B-250 San Rafael, California, 94903 May 19, 2010 SEND AN EMAIL WITH ANSWERS TO THE FOLLOWING QUESTIONS IN ORDER TO BE ABLE TO LOG THIS CACHE. IF YOU WISH, YOU MAY UPLOAD A PHOTO OF YOU AT THE LOCATION AS WELL. 1: HOW DEEP DOES THE CREEK PRESENTLY APPEAR FROM YOUR LOCATION? 2: WHEN THE WATER LEVEL IS LOW, WHAT TYPES OF SEDIMENT IS LEFT BEHIND? GRAINY, SANDY, ROCKY, GRAVEL-SIZED, BOULDER? 3: ARE THERE ANY SIGNS OF RAPID EROSION? 4:UPLOAD A PHOTO OF YOU AT THE LOCATION AS WELL.
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