Beneath your feet lies the remnants of a once-thriving industrial operation, the Angel Island quarry rock crusher. It played a vital role in shaping not only Angel Island but also significant landmarks across the San Francisco Bay.
This Angel Island quarry began its operations in 1850. State prisoners provided the initial labor. They were housed on the prison hulk Alban. It was anchored just off the island. An event occurred in 1852 that forever changed prison management. Seventeen prisoners overpowered a guard and escaped. The public outcry influenced the decision to erect a new state prison. San Quentin was built a few years later.
The Angel Island quarry’s stone was highly sought after. In 1854, it was used for constructing the new fortress on Alcatraz. The Navy base at Mare Island used it in 1857. Later, the California Bank building at Sansome and California Streets in San Francisco used stone from this quarry.
A civilian manager oversaw the quarry. He even built a house on the island for the quarry supervisor. This civilian operation ended in 1867. General McDowell took the Angel Island quarry under military control.
The Army then utilized the Angel Island quarry’s resources. Stone was produced for construction at Fort Point. It was also used at the San Francisco Presidio. Of course stone was used on Angel Island itself. Military prisoners from Alcatraz provided quarry labor. This was especially true after 1870. The number of Army prisoners on Alcatraz had increased. Men were transported to Angel Island by boat each morning. They returned to Alcatraz in the evening.
The last known use of stone from this excavation was in 1922. Stone from the Angel Island quarry was used in the Richmond breakwater. Early sketches of Quarry Point show a substantial hill. It stood over one hundred feet high on the site of the Angel Island quarry. The hill was completely gone by the time quarry operations ceased. It had been quarried away entirely.
Around 1890, the engineering corps opened up a quarry on a rocky point on the east side of the island. The old crushing plant was steam-driven. It had a capacity of 40 tons per day. By 1913, a new plant was installed. It used electric power. The new plant’s capacity was 40 tons per hour. New bunkers were built. They had a storage capacity of 800 tons. These bunkers loaded directly to barges. Electric power was brought to the island by submarine cable from Sausalito. The equipment included a No. 5 Symons gyratory crusher bucket elevator and a trommel. Three sizes of product were made. These were screenings ¾ inch and 1 ½-inch. The new plant cost $15000. It was estimated to save the government $60000.
The rock itself was a blue-gray metamorphic sandstone in massive beds. Some partly oxidized material lay at the surface. Up to October 1913 a total of 45000 cubic yards of clean rock had been produced. 40000 cubic yards of oxidized rock were produced as well. The oxidized rock was used on roads and fills. It was estimated that there were 150000 cubic yards yet available for quarrying. 70000 cubic yards would be used for road work.
The Angel Island quarry furnished rock for concrete. It was used for construction at several of the Bay posts. These included Fort Mason the Presidio and Alcatraz Island. With sand also obtained on the island this rock was employed in constructing the new buildings of the enlarged recruit depot of Fort McDowell just above the quarry. These reenforced concrete structures represented an expenditure of $600000 for materials alone. The labor except skilled civilian foremen was furnished entirely by military prisoners.
The Angel Island quarry stands as a silent testament. It reflects the hard labor that shaped our surroundings. It provided materials for iconic landmarks. As you stand here remember the echoes of the past. Consider the landscape. The Angel Island quarry rock crusher whispers stories of industry ingenuity and the enduring power of human effort.