Strawberry Spit is a small artificial island in the San Francisco Bay

San Francisco Bay

San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...

's Richardson's Bay embayment of Strawberry Lagoon

Strawberry Lagoon

Strawberry Lagoon is an inlet within Richardson Bay, Marin County, California, USA. This location, particularly on Strawberry Spit, is a winter haul-out area for the Harbor Seal...

. It is also referred to as Strawberry Spit, although it no longer is technically a spit.

Historically the spit was a haul out area for Harbor Bay Seals. A channel was built to separate the from the mainland to isolate and therefore protect the Harbor Bay Seals from human disturbances

The landscape north and landward of Strawberry Spit is dominated by Ring Mountain, whose slopes are strewn with a multitude of boulders that include minerals such as mica

Mica

The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...

, amphibolite

Amphibolite

Amphibolite is the name given to a rock consisting mainly of hornblende amphibole, the use of the term being restricted, however, to metamorphic rocks. The modern terminology for a holocrystalline plutonic igneous rocks composed primarily of hornblende amphibole is a hornblendite, which are...

 and eclogite

Eclogite

Eclogite is a mafic metamorphic rock. Eclogite is of special interest for at least two reasons. First, it forms at pressures greater than those typical of the crust of the Earth...

.