Geology and Ground Water in North-Central Santa Cruz County, California

摘要

North-central Santa Cruz County is underlain mainly by folded sedimentary rocks. Ground water is stored in fractures within shale and mudstone formations. Fewer than 10 percent of the wells yield more than 15 gallons of water per minute. The water in most wells is moderately hard to very hard, is generally of a sodium bicarbonate or calcium bicarbonate type, and commonly has excessive concentrations of iron or manganese. Of the many geologic units in the study area, only the Purisima Formation of Pliocene age has the potential to sustain well yields greater than 100 gallons per minute.