Shutter Ridge at Lake Temescal
The Hayward Fault in Oakland, California
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
This view shows the north end of Lake Temescal behind its wide earthen dam, built in the 1850s to serve as Oakland's first reservoir. An existing lake was here at the time, occupying a downdropped block between two strands of the Hayward fault. Such water bodies are called sag ponds. The far strand ends here while the near strand passes behind the building and continues to the north. In the distance is Mount Tamalpais.
The north edge of the body of Franciscan rocks is marked by the end of the ridge. It is, in fact, a shutter ridge. As the ridge moved rightward, the course of Temescal Creek was forced to bend around it (see a map). There are many crooked creeks along the fault. Temescal Creek is bent more than a kilometer off course.
Photo (c) 2005 Andrew Alden, licensed to About.com. (fair use policy)
