The Lompico Sandstone is a sedimentary rock

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

 formation of lower to middle Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 age. It overlies the Salinian

Salinian Block

The Salinian Block or Salinian terrane is a geologic terrane which lies west of the main trace of the San Andreas Fault system in California. It is bounded on the south by the Big Pine Fault in Ventura County, and on the west by the Nacimiento Fault...

 basement rocks of Santa Cruz County, California

Santa Cruz County, California

Santa Cruz County is a county located on the Pacific coast of the U.S. state of California, on the California Central Coast. The county forms the northern coast of the Monterey Bay. . As of the 2010 U.S. Census, its population was 262,382. The county seat is Santa Cruz...

. It interfingers with and is overlain by the Miocene Monterey Formation

Monterey Formation

The Monterey Formation is an extensive Miocene oil-rich geological sedimentary formation in California, with massive outcroppings of the formation in areas of the California Coast Ranges, Peninsular Ranges, and on some of California's off-shore islands...

. These are in turn overlain by the mid to upper Miocene Santa Margarita Sandstone which is in turn overlain by the upper Miocene Santa Cruz Mudstone.

Hydrological importance

There are numerous occurrences of this rock strata including coastal mountain ranges from Northern to Southern California

Southern California

Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...

. In the coastal range of Santa Cruz County the formation has been documented in the Zayante Creek

Zayante Creek

Zayante Creek is a stream within the San Lorenzo River watershed in Santa Cruz County, California, United States. The U.S. government has designated Zayante Creek as impaired with respect to sediment. Lompico Creek, a tributary of Zayante Creek, is listed for impairment by pathogens...

watershed. The formation is often associated with groundwater recharge areas.