Iron Zoo Oil Patch

The Great Valley of California is an alluvial plain measuring 400 miles (640 Km) in length and up to 50 miles (80 Km) in width. It receives the drainage from most of the Sierra Nevada and a sizable portion of the Coast Ranges. The only natural outlet from the Great Valley is through the San Francisco Bay. As the ranges on both sides of the valley rise, the deposits washed down into the valley over millions of years have caused the valley to warp downward, tilting the older strata along its margins. The continental deposits in the valley are up to 9,000+ feet (2,750+ meters) thick and overlie ancient marine deposits that are as thick as 25,000 feet (7,620 meters). In the southern end of the valley, some of these deposits are host to economic oil reserves.

Print No. A99-7-5.