Natural Areas Locator

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What's New

San Francisco Recreatioin & Park's Description of Capital Plan Format Changes (PDF 84 KB)

Natural Areas

Corona Heights

Location: Roosevelt & Muesum Way
Established: 1930s
Size: Park: 12.6 acres/Natural Area: 9.6 acres
Park Type: Grassland

This park has some of the best views in San Francisco, but don't overlook the wonderful wildflower display that carpets the grasslands each spring.

Geology

Corona Heights' prominent red rock outcrop, visible from many parts of the city, began to develop about 200 million years ago in the middle of the Pacific Ocean. Magma emerging through the earth's crust at the spreading center between the Pacific and Farallon plates contacted sea water and cooled to form pillow basalt, the bedrock of oceans everywhere. Over the next 75 million years, radiolaria—amoebae-like unicellular organisms with silica-rich exoskeletons—lived, died, and drifted down through the deep ocean waters to the ocean floor. Eventually the combination of pressure and time turned these microscopic organisms into the rock we call radiolarian chert.

The movements of the tectonic plates eventually brought the Corona Heights rock close to shore. Sand eroding from the Sierra Nevada washed into the ocean and turned to sandstone layered atop the chert. As the Farallon plate subducted under the Continental plate, the rocks of Corona Heights were scraped off, scrambled up, and pitched onto the land.

On the northeast slope, at the base of the hill, is an excellent example of "slickensides," a smooth, polished surface between two masses of rock that is created by tectonic sliding of one past the other. Usually slickensides are found in softer rock; this example in chert is highly unusual. This slick vertical rock face can best be seen from Beaver and 15th Streets.

Cultural History

In the early 1900s Corona Heights, Billy Goat Hill and other sites around San Francisco were quarried for chert to make cheap bricks, especially by the Gray brothers, who quarried rock from the hilltop, giving it its excavated appearance. The Gray brothers were described as "constant law breakers," and were accused of injuring neighbors and damaging property with debris from illegal rock blasting. They had a brick kiln on States Street, where the remnants of the brickyard buildings can still be seen. The kiln burned during the 1906 earthquake but was repaired, and quarrying continued. In 1914, George Gray was murdered at 30th and Castro Streets by a former employee who was owed back wages. An unsympathetic jury acquitted the defendant.

Be Mindful

Corona Heights has a lot of poison oak, which provides food for dark-eyed juncos and white-crowned sparrows, and shelter from predators and habitat for many of the insects that birds feed on. However, poison oak can give humans an itchy rash. Learn to recognize this plant by its three shiny green (sometimes red) leaves and tan spine-free stems.