GZ: (37° 58.412’N 121° 32.333’W) First be aware that the drive to GZ is approximately 30 minutes one way from the next nearest cache near the Holt Post Office on Hwy 4. Also note that except for the paved road, which is a county road and a public right-of-way, Bacon Island is 100% privately owned, even the bank down to the river. Bacon Island has number unique features. (1) First, not part of the EC, but of interest is Camp 3. During World War 2 when labor was short with so many at war, among other things there was a shortage of farm labor. From GZ, if you look at a compass bearing of 247°W you see a collection of roofs. This is Camp 3. Camp 3 was built to house Japanese women internees and their children who were brought to Bacon Island in the summer to act as farm labor ( https://www.youtube.com/watch?v=vqLuq49JIVg ). (2) Now on to the actual EC. Bacon Island is the epicenter of subsidence in the Sacramento-San Joaquin Delta. The primary cause of subsidence of peat soils is that they are oxidized by bacteria. Peat soils are very organic rich, made up mostly of dead reeds built up over millennia. Before the levees were built and the soils were water logged, the lack of oxygen largely prevented the soils from being “eaten” by soil bacteria. Once the levees were built and the islands drained, the unsaturated peat soils (peat is nearly 100% organic matter) can be “eaten” by bacteria because of the now ample oxygen. Make a note the elevation difference between the crest of levee and the lowest point you can observe (Question 1 and 2). Because of the depth of subsidence, there have been proposals to turn Bacon Island (and the Webb Tract) into reservoirs. NOTE (added August 2019): WHEN GOV JERRY BROWN HAD ON THE TABLE A PROPOSAL TO BUILD TUNNELS THROUGH THE DELTA TO BRING WATER TO THE THIRST SOUTHERN PORTION OF THE STATE. ANTICIPATING THAT THE (LA) METROPOLITAN WATER AGENCY BOUGHT BACON ISLAND TO MAKE A RESERVOIR TO CONNECT WITH JERRY'S TUNNELS AND BRING WATER TO LA COUNTY. . (3) If the fields on the floor of the island are plowed, note the color of the soil (Question 3). (4) Finally, look to the northeast. In 1983 the levee of Mildred Island failed, and the owners opted not incur the cost of repairing the failed levee.
Way Point 1: (37° 58.177’N 121° 32.224’W) From the road, look below at the abandon house. The house was built on pilings at ground level. The pilings kept the house at the same absolute elevation, but he ground has subsided away from the house. Estimate the elevation difference between the floor of the house and the ground surface (Question 4).
Okay, now to log logging this EC. As per the Earthcache logging requirements, you must send to the cache owner answers to the following questions:
Question 1: The area of Bacon Island is 5,400 acres. Using your estimate of the depth of Bacon Island minus 5 feet for safety freeboard, what would the storage volume of Bacon Island be if it were turned into a reservoir?
Question 2: Assuming an average household use of 465 gallons per day per household, how many households could be supplied with water for one year?
Question 3: Organic rich soils are typically dark. What is the color of the soils in the floor of Bacon Island?
Question 4: As study has determined that the average subsidence rate of soils at Bacon Island is 0.9 inches per year. Based on the your estimate of the distance difference between the floor of the house and the ground surface, back calculate the year the house was built.
Steven J. Deverel and David A. Leighton. Hydrofocus Inc. 2010. Historic, Recent, and Future Subsidence, Sacramento-San Joaquin Delta, California.