The Islands of Interior California: The Littlest Islands of All

Red Hill with the southern Sierra Nevada in the distance

How often in life have you stepped back from the rat race and considered your life and your place in the cosmos? Wondered why you are here and what does it all mean? Do your conclusions and philosophy change over time? Or is life just such a rush that you deal with it, and look back and wonder where all the time went?

If there is one thing we learn as we delve into geology, it is that time is a relative thing. We look at someone a hundred years old, and we think of a century as a very long time. And yet a human lifetime is miniscule in the face of geologic time on earth. The world has existed for 45 million centuries. Whatever his other failings, Richard Dawkins put our existence into perspective nicely:

"After sleeping through a hundred million centuries we have finally opened our eyes on a sumptuous planet, sparkling with color, bountiful with life. Within decades we must close our eyes again. Isn’t it a noble, an enlightened way of spending our brief time in the sun, to work at understanding the universe and how we have come to wake up in it? This is how I answer when I am asked—as I am surprisingly often—why I bother to get up in the mornings." 

With that idea in mind, can you imagine how ancient we humans would look to a creature that lives an entire life within maybe three or four weeks? That's where we find ourselves today, within the smallest of California's "islands". By "islands", I'm referring to the isolated sources of water within one of the harshest deserts in the world, Death Valley and the surrounding Basin and Range Province.

Red Hill (top picture) is a cinder cone and associated basaltic lava flow situated between the Sierra Nevada and the Coso Range south of Owens Lake. The lavas are tens of thousands of years old, maybe even several hundred thousand. This area is desert today, but several times in the last two million years global cooling radically changed the climate in the region. Meltwater from the Sierra Nevada glaciers filled Mono Lake Basin and Owens Lake to overflowing, and the resulting river flowed south towards China Lake and ultimately to Death Valley.

Water is a rare phenomenon at Fossil Falls. This is a shot from several years ago on a very wet trip.

Lava spilled out across the valley floor and blocked the flow of the ancestral Owens River, and the river formed a 40 foot tall waterfall. Over time erosion attacked the lava, causing the lip of the fall to migrate upstream. Pebbles rolling in the current started grinding out potholes in the lava, some small, and some more than ten feet deep. When the climate warmed up during the last 10,000 years, the river dried up and only the potholes and abandoned waterfall remain. It's a fascinating place to explore.

But islands? The small potholes have their own kind of story, one of the persistence of life in the face of the harshest conditions imaginable. The potholes are natural collection sites, capturing windblown dust and silt as well as seeds and most importantly to this story, the eggs of small creatures, possibly carried in the mud adhering to the feet of birds. During storms water collects in some of the potholes (very small islands of water in the midst of a desert). I can imagine the birds finding water in the potholes and stopping for a drink, with the eggs washing off in the water...and eventually hatching.

Within these pools are complete ecosystems of creatures who must live their entire lives on a scale of a few weeks. It begins with birth when a pothole is filled with water and ends in death when the water evaporates. The creatures include small fairy shrimp and what I assume are ostracods, small bivalved crustaceans. These animals are the distant and yet direct descendants of the first complex forms of life that evolved on this planet some 500 million years ago, creatures like trilobites and sea scorpions. Their original ancestors were creatures of the sea, requiring water to survive. They still require water today, but water is a precious and rare commodity in the desert environment. To survive, these descendants evolved eggs that could survive years of desiccation in a harsh desert environment.

One could speculate in a slightly humorous vein that these creatures don't have a whole lot of time to consider their place in the cosmos, and don't have much of a chance to ask themselves why they exist when life is compressed to a few weeks at best. But consider how short our lives are in the face of vast time across the Universe. Are we all that much more aware of ourselves?

A Fairy Shrimp (carrying an egg sac). The "sesame seeds" are Ostracods, very small bivalved crustaceans who were in constant motion.

This is the first installment of a mini-blog series about the biological islands of interior California, an exploration of the geological conditions that allow life to survive in the harsh deserts in the vicinity of Death Valley National Park. Fossil Falls is readily accessible to travelers on Highway 395 between Ridgecrest/Inyokern and Lone Pine. The one mile gravel road is a few miles south of the rest area at Coso Junction and just north of Little Lake. The falls themselves are at the end of a quarter mile walk across the lava flow. A small and decidedly barren campground is nearby. In addition to the potholes and falls, explorers can also find petroglyphs and small shelters where Native Americans carved arrowheads and spear points from obsidian.

Out of the Valley of Death: Dreams of the Water Times at Fossil Falls

The lands east of the Sierra Nevada are dry. The massive mountain wall of granitic rock captures the Pacific storms that reach California and wrings the moisture out, leaving barren deserts and culminating in the hottest spot in the world and the driest locality in North America: Death Valley. Rocks of course are superbly exposed in this landscape, but the overwhelming impression for most visitors is the dryness.

It wasn't always this way. Climate change happens on different scales. There is the very rapid climate change that we are enduring in the present day, where major changes are taking decades rather than centuries or millennia. And then there is the kind of change that happens on a time scale of tens of thousands of years. That has been happening in the eastern Sierra Nevada over the last two million years as the northern hemisphere alternated between cold wet periods and warmer stretches. These were the Pleistocene ice ages. Evidence for at least six glacial advances can be discerned in the rocks and sediments of the Sierra Nevada, but independent analysis of ocean core sediments suggests that at least a dozen glacial advances took place (larger events tended to erase the evidence of earlier but smaller events in land deposits).

And yet the rocks retain the memory of water. Or in non-anthropomorphic language, the rocks contain clear evidence of earlier periods of wetter climate. A popular stop for geology field trips in the eastern Sierra Nevada is Fossil Falls in the Coso volcanic field between Ridgecrest and Lone Pine. The attraction of the site isn't a fossil, but the evidence of a large flowing river in the desert.

The valleys east of the Sierra Nevada are there not there because of river erosion. They exist because the crust itself has been stretched to the breaking point, and faults have formed. Some blocks sank to form deep graben valleys, while other blocks remained elevated to form the high mountains (horsts). Previously existing river systems were disrupted and vast regions no longer drained to the sea. This area of interior drainage is called the Great Basin, and it extends from the Sierra Nevada to the Wasatch Front in the state of Utah.

During the wet and cold periods the glaciers didn't reach far down into the valleys east of the Sierra Crest. But they did melt, and the meltwaters collected in lakes in the bottom of the deep graben valleys. When the cold periods lasted long enough, the lakes would fill to overflowing and spill over into the next basin. Fossil Falls are situated between Owens Lake and China Lake, with the cinder cones, plug domes, and basaltic lava flows of the Coso volcanic field in between. Lava flows from cones like Red Hill (above) occasionally blocked the river that would sometimes flow between the two currently dry lakes (Owens Lake contained a thirty foot deep lake as recently as the 1920s, but water diversions to Los Angeles caused it to dry up; it would need to be several hundred feet deep before it could spill over again at Fossil Falls).

The strangely shaped rocks then originated as the Owens River flowed and spilled over the edge of the lava flow that stood in its path. The smallest irregularities in the basalt would cause swirls and eddies in the flow, and sand, gravel and pebbles would grind at the edges of the shallow basins, eroding and deepening them. Eventually they would become potholes, and some of the potholes at Fossil Falls are immense. At least one of them tunneled ten or twelve feet down and broke through the canyon wall (below), forming a climbing challenge for canyon explorers (I proved I could shimmy up the thing a decade or two ago, so I don't need to prove it anymore...).

There is life in the potholes. When rain fills some of them, eggs of fairy shrimp hatch and for a few short weeks the small arthropods live, grow, mate, and die, leaving their eggs to wait for the next wet year.

It is strange to stand at this ancient river bed and hear only the gusts of wind. One can travel in one's mind though, and start to hear the crashing waters, the verdant cottonwood trees rustling, and the sounds of animals coming to the river for a drink. There were mammoths at the time, and horses, and camels, along with the more familiar deer and pronghorn antelope. One might have spied a Sabertooth Cat, a Dire Wolf, or an American Lion lying in wait in the hope for a meal. In the latest times, humans hunted for game in this more equitable environment. Chips of obsidian and housing rings are still present.

2005 was an extraordinarily wet year, and storms were actively dumping water into the drainage upstream of Fossil Falls. That year was the one and only time I've ever seen water flow through the gorge. The little stream could never be mistaken for the torrent that once flowed through and carved the canyon, but it was beautiful to see an echo of the water times of the Owens River system.

Fossil Falls is on Bureau of Land Management lands, and has been "developed" as a recreation site, with a small parking lot, campsite, and restrooms. The trail to the fall is not long, about a quarter mile, but it has a few rough spots. Climbing around the potholes can be a little intimidating, but the views are great from the rim as well.

Friday's Mystery Photo Explained

I was gratified by the many responses to Friday's Mystery Photo, and all of you were partly right, in that the photo was in basalt. The picture was in fact taken at Fossil Falls near the Coso Range east of the Sierra Nevada (and south of Owens Lake). During the Pleistocene ice ages, Owens Lake filled with glacial meltwater, and spilled over into the valley to the south. The river poured over a thick basalt flow. With all manner of boulders and pebbles to work with, the swirling eddies produced a dazzling collection of huge potholes. The pothole in the picture was unusually deep and narrow, and eventually broke out into the main channel about 9 or 10 feet down. The more energetic and flexible members of our party could shimmy up the tube and climb out. I am about 15 years past being able to do it anymore!

The site is not far from the "village" of Olancha, and includes a small undeveloped campsite and restrooms. The falls area was popular with early Native Americans, with stone rings and obsidian work sites, as well as a few petroglyphs in the area. After rains, the potholes also play host to fairy shrimp, who are born, live, reproduce, and die within a period of a week or two.

Nearby Red Hill is a classic cinder cone, and numerous cinders and volcanic bombs can be found in the vicinity. The Sierra Crest provides a wonderful backdrop.

The pictures above reflect how reasonable the tree mold idea was. Tree molds form when lava flows inundate forests. The lava freezes around the tree trunks, and the trees then burn, leaving behind perfect molds. I have seen tree molds of big Ponderosa Pines on Medicine Lake Highland in northern California, and they are large enough and deep enough (10-15 feet) to climb into. The two molds in the second picture are two branches from one tree, and they merge about two feet down.

Pictures of Fossil Falls in the next post...