History of Hercules, California

Hercules is a municipality in Contra Costa County. It is a suburban home for about 25,000 residents, local-serving businesses headquarters location for a global biotech corporation and a small and medium-sized businesses. The City of Hercules is part of the San Francisco Bay Area metropolitan region, which is the sixth largest in the nation. The Bay Area economy is the seventeenth largest in the world. 

Since 1972, Hercules has grown as a place to live, work and shop, exemplifying California’s pattern of housing development with single-family homes accessed by motor vehicles.  Hercules’ story over the last half-century of converting industrial land into a place for people reflects larger lessons for many places in California. 

The municipality’s name is from the Hercules Works, the chemical factory that, for a century, operated in Refugio Valley. In 1900, the town was incorporated by officers of the Hercules Powder Company. Industrial production of chemicals continued until 1977. 

This was one of the largest explosives factories in the world. The explosive products made here and the techniques of their production were profoundly important to society. Explosive chemicals were fundamental to the rise of large-scale industrial production that lifted living standards and transformed societies. Powerful chemical explosives shaped the world in which we live today. 

Hercules Logo

Hercules was the brand name of a product, dynamite. High volume manufacture of dynamite was pioneered in the Refugio Valley by the men of California Powder Works. This place, a center of innovation in chemical engineering, came to be named Hercules, after the brand name for dynamite sold worldwide. Hercules Powder Company was entwined in ownership with the monoplist E.I. duPont de Nemours; both were involved in early antitrust actions under the Sherman Act.

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    Warren H. McBryde

    Assistant superintendent of the Hercules Powder Works during World War I.

  • Before becoming the site of the Hercules Works, Refugio Valley was a province of Pinole, a 19th Century agricultural hinterland of San Francisco. In 1878 the Northern Railway arrived, and lands of the lower Refugio Valley were first acquired by California Powder Works. In the years leading up to the Civil War, California industrialists had founded the California Powder Works in Santa Cruz to assure the supply of black powder explosives for mining and construction. Hercules Works in the Refugio Valley was to produce the new high-order explosives, and a range of explosive and other chemicals over the next century. 

    Leading up to 1878, the new people of Pinole were Americans; the old people were descendants of the Mexican or Spanish settlers. Pinole had been transformed by the Americans arriving in the Gold Rush of 1848 and after California statehood in 1850. 

    The town of Pinole is among the earliest European-settled places in California. It took shape as an agricultural port during the span of Mexican Alta California. With a Spanish land grant in 1823, it began as the Martinez family ranch engaging in the California commerce of the time: trading cattle, hides, tallow and produce for finished goods in sail-powered oceanic trade. 

    The lands of the Pinole and Refugio Valleys were contested territory during the span of Spanish occupation from 1772 to 1823. Alta California, the colonial project of Spain, had reached the Pinole and Refugio Valleys in 1772 with the Fages expedition. Indigenous Karkin and Huichun peoples were coerced into the Spanish mission system of servitude. 

    At this first European contact, the Bay Area was one of the most densely populated places in North America. Remains of indigenous works have been documented in the Pinole and Rodeo watersheds, and along Carquinez Strait. HHS holds no records of such sites in Refugio Valley. 

    Humans occupied these lands about 6,000 years ago. The original peoples were tribal, lived in villages and were hunter-gatherers on land and water. To catch waterfowl and fish, they launched boats of tule reeds from the wetlands of the San Pablo Bay shoreline and Carquinez Strait. 

    Today’s sharp shoreline was defined in 1878 by the Northern Railway’s tracks. Before then, the shoreline from Point Pinole to Carquinez Strait was a series of marsh wetlands punctuated by low bluffs. From 1850 to 1930 San Pablo Bay itself was altered by the deposition of enormous quantities of silt produced by hydraulic mining for gold upstream in the Sierra foothills. 

    Forty per cent of all California’s surface waters flow through the Carquinez Strait and San Pablo Bay. San Pablo Bay is part of the San Francisco Bay Estuary, the largest on the Pacific Coast of the Americas. It reached its current size about 12,000 years ago due to sea level rise. Previously a river valley, it was filled as the Ice Age glaciers melted.  A mighty river had flowed through the valley from Carquinez to the Golden Gate from 620,000  years ago, when a wall of water from an ancient inland lake broke through the gap between today’s Crockett and Benicia. Then, the Pacific Ocean surface was 500 feet lower than today. 

    Refugio Valley is the watershed of Refugio Creek, located between Pinole Ridge to the southwest and Franklin Ridge to the northeast.  The valleys of Refugio, Pinole and Rodeo  run generally northwest - southeast, at the feet of a series of low ridges descending into San Pablo Bay. These ridges are the northern extent of the Berkeley Hills, a defining geologic feature of the Bay Area. A few miles north of these ridges is the boundary between two major geomorphic provinces of California: the Coast Range meets the Great Valley.  

    The Berkeley Hills, with its three northern valleys, rose from the Pacific Ocean seafloor two million years ago. Almost all of Refugio Valley’s soils and rocks are Miocene shale, formed as sedimentary rock sixteen million years ago. In a few isolated places, rocks from other ages can be seen, such as older volcanic “Pinole tuff” and marine terraces of younger sedimentary rock. 

    The San Francisco Bay region is located at a convergent boundary of tectonic plates. Its hills, valleys and waters were shaped by the collision of the North American and Pacific plates, which were driven by plutonic forces deep in the Earth 28 million years ago.