Helley, E. J.

About the author


Preliminary quaternary geologic maps of Santa Clara Valley, Santa Clara, Alameda, and San Mateo counties, California: A digital database

This digital map database, which is compiled from previously unpublished and open-filed U.S. Geol. Survey reports (Wesling and Helley, 1989), represents the general distribution and identity of Quaternary deposits in eight 7.5 minute quadrangles in the

Quaternary geology of Alameda County, and parts of Contra Costa, Santa Clara, San Mateo, San Francisco, Stanislaus, and San Joaquin Counties, California: A digital database

Alameda County is located at the northern end of the Diablo Range of Central California. It is bounded on the north by the south flank of Mount Diablo, one of the highest peaks in the Bay Area, reaching an elevation of 1173 meters (3,849 ft). San Fran

Quaternary geology of Contra Costa County, and surrounding parts of Alameda, Marin, Sonoma, Solano, Sacramento, and San Joaquin Counties, California: A digital database

Contra Costa County is located at the northern end of the Diablo Range of Central California. It is bounded on the north by Carquinez Strait, through which flows 27 percent of California's surface water runoff. San Francisco Bay forms the western boun

Geologic maps and structure sections of the southwestern Santa Clara Valley and southern Santa Cruz Mountains, Santa Clara and Santa Cruz Counties, California

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (scvmf.

Preliminary maps of Quaternary deposits and liquefaction susceptibility, nine-county San Francisco Bay region, California: a digital database

This report presents a preliminary map and database of Quaternary deposits and liquefaction susceptibility for the nine-county San Francisco Bay region, together with a digital compendium of ground effects associated with past earthquakes in the region. T