The Karst Topography...of California? Getting Filthy Rich from Karst in Columbia

The Fricot Nugget at the State Mineral Museum in Mariposa, California

As I noted in the last post, California has some unique landscapes that are unfamiliar to most visitors, specifically karst topography. Karst results when a region is underlain by limestone or marble. The formation of caves is sometimes revealed at the surface when the roof of a cavern collapses, forming sinkholes and related features. At Chaw'se in the last post, we saw how karst topography was utilized by the Miwok people. Today we look at how another culture used karst, and in the process nearly brought about the end of the Miwok and other native peoples in California. It was all about gold.

The southern Mother Lode in the vicinity of Columbia and Sonora.

The western part of the Sierra Nevada is composed not of granite, but of metamorphic rock like slate, marble and metavolcanic greenstone. The metamorphic rocks contained widely disseminated bits of gold, but hydrothermal activity related to the intrusion of granite in Mesozoic time concentrated the gold into veins of quartz and other minerals. The veins came to be known as the Mother Lode, and they were the source of riches and misery. In most cases the miners were after gold-bearing river gravels along rivers that flowed through the Mother Lode, or they developed mines that cut directly into the quartz veins. When the easy gold was gone from the rivers, they expanded their search into unexpected areas. One of those places was the ancient riverbeds of another era, long before the present day Sierra Nevada existed.

Fifty million years ago, the Sierra Nevada didn't not exist as a mountain range. There were the eroded remnants of an ancestral Sierra Nevada that developed during the late Paleozoic and early Mesozoic eras when masses of land slowly mashed into the western edge of North America, and when subduction zones produced magma that eventually became the granite of the high Sierra. Those mountains were gone, and instead there were slow-flowing rivers that had their origin in what is today central Nevada, with hints of headwaters much farther away, perhaps even Canada. The rivers flowed into a coastal complex that was characterized by swamps, jungles, and sandy beaches. These ancient rivers were ultimately diverted here and there by lava flows, which forced the water into new channels that became today's rivers, like the Stanislaus and Tuolumne. The ancient river gravels that remained were perched on high flat ground between today's river canyons. The gravels often contained gold, but something very odd happened at the site of Columbia State Historical Park. It involved karst topography.

The rocks near Columbia form a landscape unlike those found anywhere else in the Mother Lode, or anywhere in California for that matter. The limestone that formed in Paleozoic oceans 300 million years ago was recrystallized by heat and pressure into marble. Groundwater moved through cracks and fissures in the marble, widening the fissures, and in some cases forming caverns. A channel of the ancient rivers flowed over the roughened surface, and the fissures captured stunning amounts of gold. Eventually the rocks lay covered by two or three meters of soil and gravel. Until the miners found the gold...

The gold deposits at Columbia were unbelievably rich. According to some estimates by geologists of the California Geological Survey, some 4 million ounces of gold, worth about four billion dollars at today's prices was mined here. The entire production of gold in California over the last 150 years amounted to about 110 million ounces, so this one mining area produced a significant percentage of all the gold mined in California.

This gives us an explanation for the strange landscape around Columbia. The miners had very little water from local sources, so flumes and penstocks were constructed to bring water from higher parts of the Sierra Nevada. Instead of using sluice boxes or pans, the miners shot water cannons at the soils, moving vast amounts of sediment and quickly exposing the gold (this was called hydraulic mining). Parts of the town were built on gold-bearing soils, and there was the occasional suspicious fire that destroyed buildings, allowing the miners to blast away a bit more ground. What they left behind was a kid's wonderland of boulders, fissures, and small caves that is every bit as fun as Tom Sawyer Island at Disneyland (I'm disappointed that I didn't grow up as a kid around here. I had to settle for Tom Sawyer Island at Disneyland...).

It's probably no surprise to realize that the Gold Rush was a disaster for the native cultures in California. The indigenous people already been decimated by European diseases and unfortunately some of them lived in gold country. They never had a chance against the influx of tens of thousands of miners from all over the world. Some tribes disappeared entirely, and others barely hung on to their lives and culture.

Columbia hung on as a town after the gold deposits gave out, although the downtown area fell into disuse. In the 1930s, efforts began to make the area a state park, and in 1945 the town center was established as Columbia State Historical Park. The stores and restaurants were refurbished and visitors are treated to park employees and business owners in period dress. And a dandy candy store that is often the only business still open when our students arrive in town at the end of our field trip.

Such a Peaceful Scene...and the Birth of Horrific Destruction

A beautiful serene stretch of river on a sunny spring evening. How could anything like this be associated with the extermination of not just a culture, but of many cultures? How could this be linked to one of the most environmentally destructive periods in our state's history? Yet it is...

In late January of 1848, James Marshall had a contract with John Sutter to construct a sawmill on this stretch of the American River near Coloma in the Sierra Nevada foothills of California, and on January 24th, he was realigning the millrace to get the sawmill working properly. They let the river do some of the work by letting water flow through the culvert all night, and in the morning he and his workers found yellow flakes of metal in the bottom of the millrace ...

On February 2, 1848, far to the south in Mexico, the Treaty of Guadalupe Hidalgo was signed, ceding California to the United States in the aftermath of the Mexican-American War. This strikes me as one of the stranger chronological coincidences ever.

Word spread quickly about the gold in the Sierra foothills, and the rush was on. Sutter's Mill didn't operate for very long. It was essentially abandoned by 1853, and all surface evidence was swept away during a flood in 1862. Many years later, the foundation timbers were excavated, allowing archaeologists to calculate the dimensions of the mill. A replica was constructed on the site in 1967, and the original timbers have been put on display (below).

The village at Coloma is now a state park that commemorates the discovery of gold and the rush that followed. There is a fundamental fascination with the yellow metal that caused hundreds of thousands of people to abandon their homes to seek a fortune in the gold fields of California. Legends abound of miners who found giant nuggets and rich pockets that made them instantly rich. Other legends tell the story of bandits and desperadoes. Few stories are ever told of the people whose culture disappeared into the mists of history without ever being recorded. The Native Americans of California, who may once have numbered over a million people, had already been decimated by European diseases, but for some cultures the Gold Rush was the last nail in the coffin.

The 1967 reconstruction of Sutter's Mill in Coloma

The Gold Rush did not last for very long. By 1853, the rivers had been overturned in the quest for the yellow metal, and the miners were beginning to disperse in hopes of finding ores in eastern California and across Nevada. The attention of the mine owners and investors shifted to methods of gold extraction that were more efficient and even more destructive.

Gold-bearing gravels could be found on ridge lines where ancestral rivers once flowed prior to the main uplift of the Sierra Nevada. The miners couldn't efficiently work the deposits because of the lack of water. Mining companies put together a system of flumes and canals in the high country to bring water to the gravels, and one of the most destructive kinds of mining ensued: hydraulic mining. A water cannon, called a monitor, was pointed at the cliffs with the gold bearing gravels, and the explosive spray washed away the gravel into a large tunnel. Large riffles filled with mercury trapped the particles of gold, and the waste material was dumped into the nearby rivers.

A monitor (water cannon) used in hydraulic mining at North Bloomfield.

Millions upon millions of cubic yards were washed away. In the scene below near Interstate 80, the landscape was once level with the white cliff in the far distance. The valleys downstream were choked with debris, and silt filled the floor of the Central Valley. Floods became commonplace as river channels filled with silt and overflowed. Mud filled parts of San Francisco Bay to the extent that it is only about 70% of its original extent. Mercury that escaped from the mines contaminated the sediments, and continues to be a problem today. Hydraulic mining was so destructive to the environment that it was essentially outlawed in 1884.

And then there were the dredges. It took the mining companies a long time to figure out a way to find the very fine gold particles that filled sediments in the Central Valley. The first successful dredge went into action in the late 1890s, and profitable production continued into the 1970s. The dredges were large factory barges with a system of shovels on one end, a waste conveyor belt on the other, and a series of sieves and mercury coated copper plates in the middle to trap the microscopic particles of gold. The dredges were floated in a pond, where they dug away at one end, and filled in the other. In this way, they "sailed" across parts of the Central Valley, producing huge rock piles where fertile soils once existed. Huge swaths of land were ruined in the chase for the elusive metal.

The hard rock mines of the Mother Lode had their own problems. The first mines were dug in 1849, and they were active until 1942, when presidential orders shut down the mines for strategic reasons. A few tried to start up again after the war, but were ultimately unsuccessful. The miners brought huge amounts of ore to the surface, where the rock was crushed to a powder in stamp mills and treated with mercury or arsenic to tease out the gold (cyanide is used today). The mine dumps are toxic, not only with the mercury and arsenic, but also the acids produced by exposure of the sulfide minerals in the gold veins to oxygen in the atmosphere. Clean up efforts are still ongoing today, 70 years after the mines closed.

The mines weren't just damaging to the environment. The miners themselves were subject to constant dangers from explosions, cave-ins, falls down shafts, and the gold miner's equivalent to black lung disease: silicosis, a deadly lung disorder caused by breathing in fine quartz dust.

Source: Kennedy Mine Foundation

Today the Mother Lode is a tourist destination, and the miners have achieved a sort of legendary status. The heritage of the Gold Rush is more equivocal: the destruction of cultures, and the environmental devastation of a wide swath of the Sierra Nevada foothills, the Central Valley, and San Francisco Bay. And yet, every time I take a field trip through the Mother Lode, I can't help but look through the mine dumps for the bright yellow gleam of the strange metal.

The Fricot Nugget, the largest surviving nugget from the Gold Rush era. Thieves attempted to steal the nugget last year, but failed. They still made off with numerous other beautiful specimens.

Cancel Columbus Day...or make it something better...

This picture and the "Cancel Columbus Day" caption landed in my facebook account, and I think it is a great sentiment. I agree there are better things to celebrate...not only was it the start of the near-extermination of a continent full of people who had already "discovered" the land, but the guy was on a commercial venture. The holiday is an outmoded tradition that is meaningless to most people, and grossly insulting to many people. One could argue that we need a holiday for many reasons: religious beliefs account for a few (which also celebrates one group over another), and important national events are another (we celebrate Memorial Day so we can thank our family members and friends who served in the military). And in a capitalist country that has come to dishonor the workers who make the oligarchy rich, we still hang on to Labor Day. We remember the birthdays of people who brought out the best of our country: Washington, Lincoln, and Martin Luther King. I find this appropriate.

How about celebrating a true moment of national exploration? One that changed everyone's perception of the planet? It seems to me that if this country values science and technology as an accomplishment of the human spirit; conquering disease, improving standards of living, and journeying where no one has gone before, then we should have a day that celebrates our nation's greatest scientific adventure. My thought is that we should set aside the day we landed on the moon in 1969. Our country set a communal goal with JFK's speech at the beginning of his presidency, and against huge odds we succeeded. Admittedly, the race to the moon involved trying to outdo the USSR, but I doubt that fighting communism was the foremost thought of the scientists and engineers who got us onto our planetary neighbor. And the effort resulted in vast advances in science across many fronts (not the least of which was geology).

I don't care much for Columbus. We should be celebrating something truly meaningful, and I think science should have such a day. What do you think?