Story and photos by Thomas Atkins

The impressive cliffs of Table Mountain stretch from Sonora Pass to Knights Ferry and were created by an ancient lava-filled river channel.

Of all the numerous geological wonders in Calaveras and Tuolumne Counties, Table Mountain is by far the most prominent. One of their most unique landforms, this long, flat-topped ridge, or really chain of ridges, extends over fifty miles throughout the region. In some places this mountain rises over a thousand feet above the surrounding countryside and is up to a quarter mile wide. Stretching from Knights Ferry to Sonora Pass this monstrous wall of rock dominates the landscape, and one can’t help but be drawn to its overwhelming presence. While some prefer its steep, jagged walls for rock climbing, others favor its level, table-like surface for hiking while admiring its views and its multicolored carpet of wildflowers that somehow manage to thrive in this rocky environment. However, in the mid-1800s, early settlers of the area were drawn to this unusual rock formation for much different reasons…gold!

By 1850 gold fever was raging across California, and Calaveras and Tuolumne Counties were swarming with miners in search of this precious metal. Due to the massive amounts of gold produced in these counties, the region was soon dubbed the Mother Lode and every river, creek, stream, gulch, ravine, mountain and hill were stripped clean as miners tore apart the earth in hopes of finding any trace of the “yellow stuff.” Over the next 70 years these counties constantly echoed with the sounds of shovels, picks, stamp mills and dynamite, as tunnels, shafts, dredging and hydraulic methods of mining drastically transformed the landscape. But these land-altering techniques were nothing compared to the earth-shaking event that formed Table Mountain. For a short period of time this foreboding fortification of rock appeared to be unyielding, but with “gold fever” in the air, miners would stop at nothing to strike it rich, and it didn’t take long for them to turn their attention to this remarkable landform…especially once they discovered how it had formed.

Looking up through a mineshaft near Table Mountain one can see smooth rocks left behind from the ancient river.

Geologists believe that Table Mountain was created over nine million years ago when a gigantic volcano erupted near Sonora Pass. During this era, volcanoes were supposedly numerous and active, but this one was by far the biggest and its eruption soon reshaped the landscape of Tuolumne and Calaveras Counties. Today, all that remains of the colossal volcano is a massive twelve-mile long caldera, known as the Little Walker Caldera, which can be seen on the eastern side of Sonora Pass.

As this volcano erupted, liquid magma followed the path of least resistance and rushed down the mountainside into a giant river, which once flowed down the western slopes of the Sierras. It must have been a grand sight when this river of fire came rolling down from its volcanic fount and settled and cooled in the lower elevations of Tuolumne and Calaveras Counties, filling the river canyon and all but the highest hills and peaks. In fact, much of the land around Table Mountain today was once covered with over 300 feet of volcanic mud!

The clear, cold water within the main tunnel of the mine would often reach depths of over two feet.

This volcanic mud and lava filled the ancient riverbed as far down as Knights Ferry, where it stopped and began to cool and harden, leaving behind a rocky replica of the ancient river. With the old river channel blocked, the water from the mountains now had to find new routes down to the valley, forming new rivers such as the Stanislaus. These rivers began to erode the softer material surrounding the hardened lava, and after millions of years of this process, the remains of this ancient lava flow became very evident, which we see today.

The miners soon realized that this snake-like formation was nothing more than a giant time capsule, preserving its gold laden gravel beds for millions of years. With the greatest river of Tuolumne and Calaveras Counties locked below the rugged ridge, they were eager to break the lock and partake of the buried treasure.

One of the hundreds of bats living within a Table Mountain mine.

According to “Tuolumne County, California”, which was first printed in 1909, the first discovery of the river gravel under the lava-capped mountain was in 1855 while miners were sinking a shaft near Shaw’s Flat. Soon mining claims surrounded Table Mountain as tunnels and shafts of great lengths were driven through the earth to reach the gold rich gravel of the old river channel. However, cracking into this prehistoric vault was not always an easy process and the hard shell of this intimidating fortress discouraged many of the miners. Often, the mines never reached the ancient riverbed, and those that did, would often be flooded out due to the overwhelming water flow. It was a costly procedure and many of the mines were shut down due to high expenses.

The mines with the greatest success rates were those that had tunnels driven at precisely the correct grade to permit drainage of the water table. The few mines that were able to break into this lost riverbed and reach the untouched gravel beds often extracted large quantities of gold. Between 1850 and 1870 Tuolumne County was one of the leading gold producers in the State and at least $151,175,000 (about 7,338,600 ounces) of placer gold was produced before 1899, most of which came from the gravels in the Columbia Basin and the Table Mountain channel in the Jamestown-Sonora area. In the early 1900’s the State Mining Bureau estimated that Table Mountain held three million dollars in gold per mile!

A narrow section within the mine.

The richest Table Mountain mine was the Humbug Mine on the east slope of the mountain, which had a tunnel of around 3,000 feet in length. Yet a massive lawsuit broke out when the New York Mine, located on the opposite side of the mountain, broke through into the tunnel of the Humbug and arguments arose about who owned what. Other famous Table Mountain mines that produced millions of dollars worth of gold were the Rawhide, Roseleta, Boston, Alpha, Omega and Montezuma mines.

As tunnels continued to pierce the mountain’s side these mines continued to uncvoer the costly metal…but gold wasn’t the only thing that the miners came across. Clues to the past have also been found within the ancient river as Table Mountain tells its secrets to geologists “in mute but eloquent language about the interesting story of prehistoric man, of extinct animals, of remarkable fauna and of wonderful flora, all hermetically sealed in a tomb strewn with gold and made of melted stone,” explains the 1909 book. “Below the lava is 200 feet of sand, conglomerate and pipe clay. Below this is the auriferous gravel. The pipe clay has been found to be rich in fossil plants and leaves and in solidified wood, bones, tusks and teeth of primitive animals.” While the Table Mountain mines were worked, miners found hundreds of stone artifacts, and, more rarely, human fossils.

River rocks mixed in with volcanic mud cling to the side of the tunnel walls.

Yet as the years advanced and the mining boom faded into history, access to these hidden treasures became abandoned, overgrown, and forgotten. However, if you know where to look, there are still tunnels that can take you into the heart of Table Mountain. Having stumbled upon one of these portals to the lost riverbed not long ago, I was excited to explore the under workings of this magnificent stretch of mountain and planned a trip with my friend to journey into the center of this prehistoric world.

Upon reaching the dark and damp entrance of the tunnel, we could instantly feel a drastic change in temperature from the warm spring day to the cool depths of the mountain. Shining our lights into the passageway we could see remains of ore cart rails through the crystal clear water flooding the tunnel floor. Leaving behind the comfort of sunlight, we stepped into the chilling water and began our trek into the unknown.

It didn’t take long for the light from the entrance to disappear and we relied solely on our headlights as we waded through the knee-deep water, which created a haunting echo as it splashed against the tunnel walls. Eventually we reached the ancient river channel and it was pretty amazing to see that underneath the hard, jagged mass of lava were thousands of smooth river boulders worn down by the ancient river. Huge rooms opened up where miners had once dug into the rich gravel deposits, and the ceiling extended a good fifty feet overhead. Piles of rounded rocks were stacked throughout the passageways and feeling their smooth surfaces from being tumbled in the ancient river made me think of what the scene must have looked like millions of years ago.

If I was living back when this river was still flowing, my trips to this region would’ve been much different, and instead of bringing climbing gear and flashlights my gear of choice would’ve been nothing more than a fishing pole. I imagined massive, hundred pound fish swimming through this once great river channel and it made me wonder what may be lurking in the deep, dark water shafts along the edges of the tunnel. We soon discovered, however, that our attention didn’t need to be focused on what was below, but rather on what lurked above.

After a few more bends in the innards of the hollowed out mountain an awful stench began to fill the tunnel and faint noises could be heard coming from the depths. The smell continued to increase and was almost unbearable when we came to the source. Entering a large room we were confronted with the culprit of the ghastly odor as we gazed upon a massive pile of bat guano towering over six feet tall. Looking up we noticed hundreds of bats clutching to the ceiling and as our lights pierced the darkness the room exploded into squeaking, screeching, fluttering, flapping and pooping chaos as the bats circled the cavernous room. Although it was fascinating to see that many bats in one place, it didn’t take long for us to decide that we had traveled far enough into this underground world and we were quite happy upon returning to the sunlight and the sweet smells and sounds of spring.

On our hike back to the truck we walked in the shadow of this prehistoric structure of stone passing miles of buried secrets that may never be found. It makes me wonder how much more gold or clues to the past are locked beneath this mighty vault, and if man will ever attempt to break into it again. With gold reaching over $900 an ounce, it may only be a matter of time before new methods are invented to steal the remaining treasures buried below. Yet until that day comes, this great mountain will continue to guard and cherish its treasures with pride, giving up its secrets only to those who journey beneath the table top.