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New USGS Publication Reveals Human Influence on San Francisco Bay Floor
The U.S. Geological Survey (USGS) recently released "Shifting Shoals and Shattered Rocks—How Man Has Transformed the Floor of West-Central San Francisco Bay" (USGS Circular 1259), by John Chin, Florence Wong, and Paul Carlson. The new book takes readers beneath the waters of San Francisco Bay to see a bay floor greatly modified by humans since the California gold-rush days of the 1850s. Recent high-resolution mapping provides a detailed image of sandy dune fields, rocky pinnacles, and extremes in relief—much like features on dry land. The new map data reveal evidence of large-scale, long-lasting excavations dug in the 1910s and 1930s to provide fill to enlarge the Marina District in San Francisco and to create Treasure Island off the San Francisco-Oakland Bay Bridge. Rock pinnacles in western San Francisco Bay that lie in or adjacent to major shipping lanes have been lowered by blasting several times in the past. Depressions in the bay floor have served as economical, but rapidly filled, targets for disposal of construction and other debris. Sand beds on the bay floor are a major resource that is mined for construction. The book includes a folded poster containing a three-dimensional image of the bay floor, and a set of 3D glasses.
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in this issue:
Drilling Monitoring Wells in the Dry Tortugas American Samoa's Resilient Coral Reefs Seepage Samplers in Ashumet Pond
Gulf of Mexico Vulnerable to Hurricanes
Exhibit Designers Interested in Hurricane Research USGS Hosts Science-Learning Session
Deep Water Coral Research Workshop
Four Publications Win Shoemaker Awards Gene Shin Wins Shifting Baselines Contest
Elena Nilsen Joins Coastal and Marine Geology Team USGS Vessel To Test Counter-Terrorism Equipment
Human Influence on San Francisco Bay Floor |
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U. S. Department of the Interior | U.S. Geological Survey
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