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.

Where the River No Longer Runs, Life Persists: Fossil Falls in the Eastern Sierra Nevada

Red Hill near Fossil Falls, with the crest of the Sierra Nevada in the distance.

The Sierra Nevada is the largest single block of rock in the United States. It takes the shape of a huge 400 mile long westward tilting range reaching elevations exceeding 14,000 feet. As such, it acts as a gigantic barrier to Pacific storms. The lands to the east are dry and largely barren. One high mountain range after another, like the White and Inyo Mountains, or the Panamints, capture what little precipitation remains, so that Death Valley is left as the driest place on the continent.

A few streams originate near the crest and flow into the Owens Valley. For years these streams fed the Owens River which filled Owens Lake, covering just over 100 square miles to a depth of 30 feet or so. From there the water could only evaporate or sink into the ground. Today the lake is dry, the victim of water diversions that sent Sierra water to Los Angeles. The lake would have to fill to a depth of 200 feet before spilling over into the next basin at China Lake. That would require much more precipitation than happens in the present day.

Upstream portion of Fossil Falls

But the climate has not always been like it is today. At various times during the last 2 million years the world cooled, and glaciers grew in the Sierra Nevada, eventually covering as much as 30% of the range. The glaciers would melt and some 10% of the Sierra water would drain into Owens Lake and spill over into China Lake, eventually reaching Death Valley. Rivers once flowed across the barren desert.

The rivers were like a highway for life. At some point in time, they connected with the Colorado River and numerous species of fish entered the waterways: trout, chub, pupfish and many others established populations in the streams and lakes of the Sierra and eastern desert valleys. As the glaciers receded and disappeared, so did the rivers and lakes of the desert. The few fish populations that survived did so in springs and Sierra streams. For the most part, aquatic life withered away in the desert heat.

There was another element to the story. The extensional forces that broke up the crust and formed the desert valleys produced fault lines, and provided conduits for lava to reach the surface. Volcanoes formed in many areas of the desert, including impossibly large calderas like the one at Mammoth Lakes, but in other places, the volcanism was less explosive. South of Owens Lake, there were a number of basaltic lava flows extruded within the last 130,000 years or so. Some of them crossed and blocked the Owens River. The rivers developed channels across the lava  flows, and in one place, the waters poured over a forty foot wall, forming a waterfall.

The waters carved a channel in the solid basalt, and swirling gravel and boulders carved deep potholes. Fossil Falls, just a short distance off of Highway 395 near Red Hill cinder cone is what remains of this now extinct river. It is a fascinating place to explore, and was one of our stops on our journey to Death Valley a few weeks ago.

There is little to suggest that aquatic life could survive here, but the potholes play host to a surprising survivor of wetter days. Fairy shrimp are small branchiopods that lay eggs that can survive long periods of dehydration. They lie in the sediment in the bottoms of potholes at Fossil Falls, and on the rare occasions that rain fall, water fills the potholes. This sets off a race for survival as the eggs hatch, and the organisms try to reach adulthood and reproduce before the pitiless sun dries up the water in the holes. It's a hard life, but they've survived this way for thousands of years.

It had rained a week before our arrival and water stood in a few of the potholes. I took a close look, and the  small pools were teeming with life. I couldn't get any good pictures, but a video I took shows the action. There are longish gray shrimp and some kind of very small swimming creatures at the water's edge. It's is amazing to see life persisting in the most difficult of environments.