Levees in the Delta Earthcache EarthCache
Hidden : 9/24/2009
Difficulty:
1.5 out of 5
Terrain:
1 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

This Sherman Island Road detour only takes you about 1 mile off of Hwy 160 as you’re headed to or from the East Bay area. The road gives you a great view of the delta, and the only people you’ll need to share the pull-offs with are the fishermen.

The view around you is much different than if you had lived or worked in this area prior to 1930. In those days, the geological “cycle” of spring rains, floods, sedimentation, and evaporation would have at times covered this island, and at other times, left a rich dark exposed peat formation beneath your feet. In fact, geologists believe that the agriculturally rich peat formation in the fields to your left began about 6500 yrs ago, and that at one time, most of the islands in the delta system contained over 9 meters deep of peat. Sea level was lower back then, so what we now call the delta would have likely been one marshy mass of land that dried in the summer and was wet most of the winter and during flooding. Because peat is believed to only form at or slightly below sea level, geologists believe that approximately 6 meters of natural geologic subsidence (peat formation) has occurred in the delta during the past 6500 years, forming as the global sea levels have risen (glacial melt, etc.)

The delta system of islands is in reality an ancient alluvial fan lowering the overall ground level of the islands. As the island “sinks” the levees receive increased pressure from the surrounding water sources and massive repairs are needed to maintain the water-free interior of the island. Some geological reports believe that this man-made change to the area’s naturally occurring geological process are leading to increased stresses on the levees, which if several broke simultaneously, could lead to a drastic change in the areas “look” and change the freshwater conditions for vast areas of California.

Congrads to Plant Peddler for FTF!

Logging Requirements:
Send the answers to #1-#4 to me through my geocaching profile.

1. List the name “GC1Z2Z4 Levees in the Delta Earthcache” in the first line of your email. Also, list the number of people in your group.
2. Is the delta water to your right higher or lower than the fields / islands to your left? Based on reading and observation, what has created the current elevation difference between the two sides?
3. What would be the potential economic and topographical impact if the surface you are standing on were to give way to the forces of nature?
4. (Per current gc.com guidelines, photos are no longer allowed to be required. HOWEVER they are encouraged, since they can help clarify that you have visited the location if your other logging requirement answers are vague). Post a picture of yourself and your GPS with your log that shows the delta farmland and bridge behind you DO NOT show any of the pertinent information in your picture.

I will only respond if you have incomplete logging requirements. Go ahead and log your cache

Resources:
US Department of the Interior US Geological Survey (visit link)
GSA (visit link)
Wikipedia (visit link)

Additional Hints ()

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Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

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