By Lee Roddy

Most Californians know that the Gold Rush of 1849 brought hordes of miners to seek the precious metal, but how many know how the gold originally got into the Sierra Nevada Mountains?

It seems that many people back then didn’t care abut that. It was enough to know that gold was discovered there. That was such a powerful catalyst that it led to a cultural clash which destroyed the rancho period and decimated most of the Indians who had lived here for a thousand years or so.

It appears that even today not many people know the answer to something that so dramatically impacted California. Perhaps that’s because the facts are still hard to come by, but seashells in the Sierras may provide a clue about the gold’s origin.

Fossils of sea creatures have been found up to the 5,000 foot elevation in the Sierra Nevada Mountains. That ties in with studies of geology and plate tectonics which show that ancient Sierra rivers ran in a different direction from those of 1849 and today.

My search for the origin of gold in California took me to the fascinating Kentucky Mine and Museum on Highway 49 at Sierra City. That’s where I got my first clue. Curator Anne Eldred (a very knowledgeable person) said that I could find some sea fossils in a road cut a little farther up the highway near Salmon Creek and before Bassett’s Station. 

She also suggested some books which I bought and read along with those already in my home library.

William E. Brewer, a California tourist, wrote in 1861 of exploring the Santa Susana Mountains where he found “oyster shells by the cartload, clam shells, in fact,

many species, including oysters.” (Page 46, Up and Down California) A short time later,

not far from Mission San Buenaventura, in a high, rocky ridge, Brewer gathered large clam shells, barnacles, and conch shells. (P. 49)

On his further travels, Brewer refers to gold in the Sierra Nevada Mountains. “It appears,” he wrote, “to have been up heaved, and then furrowed by water into great canyons, valleys and gulches. The gold is disseminated through the slate rock… (or quartz veins).” His observations are being confirmed by modern geologists.

I have been reading and writing about our state’s history since a high school teacher turned me on to the subject. But in all those years since then, I never found a book or met anyone who could answer that question about the origin of California’s gold – until recently. Even then, I found disagreement between authorities.

At least some of the gold originated in the ocean, according to one source, although denied by another. This view is that the gold was thrust up from inside the earth’s molten center.

The presence of seashells in California’s mountains testifies to the fact that this area had once been on the ocean floor. But how did the gold get there with the sea shells?

The moving ocean floor concept developed out of 1960s when the theory of plate tectonics began to evolve. Instruments in the modern science of oceanographic geology discovered that the ocean floor is like an immense conveyer belt creeping along at about two inches a year.

In Roadside Geology of Northern California, authors David D. Alt and Donald W. Hyndman of the University of Montana’s geology department explained how the moving ocean plate over-rode the land, scraping off the ocean bottom and mud,

In simple laymen’s terms, over millions of years, the leading western edge of North America collided with the floor of the Pacific. Something had to give, and that had two possible results: (1) part of the ocean floor was forced under the land or (2) the opposite occurred, (called subduction), where the plate under pressure was forced beneath the land with the seashells and “free” gold, or particles that had existed in the water.

Tracy I. Storer and Robert L. Usinger’s Sierra Nevada Natural History declares that the Sierras consist essentially of a massive granite block that tilted so that the western side has a gradual slope.

Today’s major California Rivers in the Sierras primarily flow from east to west. Early gold seekers mostly prospected in or near these mountain sides and streams trying to take advantage of tertiary river channels. They did not know that when the

Sierras uplifted eons ago; the mountain rivers ran more north to south. Much later, granite was intruded into the mountains followed by an uplift and unimaginable lava flows that buried the primitive river channels and changed the major rivers’ direction of flow.

That raises the possibility that those long-vanished channels could still contain vast quantities of gold. Is it possible that the reason Forty-Niners never really found the true Mother Lode (for which they diligently searched) because it is in the long-buried original river beds?

So far, the clearest explanation I’ve found of the origin of gold is in Ted Konigsmark’s book, Geological Trips Sierra Nevada. In a subheading, Origins ofthe Gold, the author explains thousands of miles of oceanic crust were swept into the subduction zones.

Most of this oceanic crust was carried under the North American plate and returned to the earth’s mantle. Part of the crust remained in the subduction zone. He adds, “Some of these rocks contained small amounts of gold.”

Konigsmark goes on to explain how intense heat and pressure of rocks in the subduction zone released gold trapped inside and into a CO2 solution. These gold-bearing solutions were forced upward by heat and injected into the overlying rock. In time, most of the gold was deposited in veins and fractures in the metamorphic rocks in the gold belt, according to the author.

Rain, snow and erosion reduced the placer gold to small nuggets or flakes. Their weight eventually deposited them in stream beds. They sank into sand and gravel where early prospectors recovered them. Hardrock mining in shafts and tunnels was required to reach the larger veins or gold where erosion didn’t take place.

Regardless of whether the Sierra’s gold originated from the ocean floor or from deep inside the earth’s molten core, the metal’s discovery in early California proved to be an incredibly strong catalyst. It destroyed the rancho period, decimated most of the native Indians, and changed the culture when hordes of gold seekers swarmed over the hills and rivers searching for a metal which had been originally deposited there millions of years before.

My search continues for more details on how gold first got into the Sierras. If you like geological mysteries such as posed by gold and sea fossils, perhaps you’ll tell me about reliable sources that will help solve this riddle.