Springtime in the California Desert: Miscellany of Life at Joshua Tree

Wrapping up a week of posts on Joshua Tree National Park, I am offering up a miscellany of life at the unique park in Southern California. A visit in the middle of May is a bit past the height of spring bloom, but there were a few flowers left to enjoy, no doubt assisted by the cool spring. It certainly didn't feel like summer out there.

One of the most dramatic flowers we saw was the ocotillo, a Colorado Desert species that lives in the lower elevations of the park. The ocotillos near Cottonwood Springs were bright with color.

One of the oddest corners of the park is the Cholla Garden at the western end of the Pinto Basin. Chollas are one of the most viciously defended plants one will ever come across. The thorns of the plant are hooked in such a way that if you brush against it, the branch will break off and stick to your skin, by the painful thorns. When you try to brush it off, the thorns stick to your hand. A comb is a vital piece of hiking equipment when hiking in cholla country.

The tendency to break off, besides leading to the "jumping" legend, is also an efficient way of propagating the species. The broken branches can sprout when they get dropped off at a new location.

In most places of the lower desert of Joshua Tree the chollas are widely dispersed, but at Cholla Garden, the chollas are growing in a nearly pure stand, probably due to perfect soil conditions.

Despite the nasty reputation, the Jumping Cholla has a beautiful flower, as can be seen below.

There were a lot of diminutive flowers to be found across the desert, one of which I didn't have any resources to identify. Any help out there?

No problem identifying this one, though. The beavertail cactus is found all over, and the blooms are distinctive...

The rich vegetation was bringing out all manner of insects and birds and reptiles. At the south entrance of the park, I caught one I've never noticed before. It turns out to be a gnatcatcher, perhaps the Blacktailed or California species.

The presence of flowers meant rich time for the hummingbirds, not a species I usually associate with the desert. I saw this one near the Barker Dam trailhead.

There are the usual reptiles. This lizard was well-camouflaged at the base of a fan palm at Cottonwood Springs. I'm assuming a Western Fence Lizard, but will appreciate corrections.

Finally, a mystery beast from the desert. I saw this...something or another...walking across the desert in the Pinto Basin. I thought some kind of wasp from the size, but I haven't a clue what it really is or what that...thing...is on its back. Anyone want to pitch in here?

Weird Geology: Accretionary Wedge #34...Our Human Nightmares

Well, how about that? I was trying to figure out how to squeeze in a bizarre shot from my recent trip to Joshua Tree National Park, and the 34th Accretionary Wedge announcement drops in my mailbox, courtesy of Dana at En Tequila es Verdad:

Geology can be strange. Outrageous. Bizarre. I'm sure you've all run into formations and landscapes and concepts that have left you scratching your head. Maybe they got less weird later. Maybe they stayed strange. But however transient or permanent that weirdness was, it got weird.

So tell us about it. Hit us with the strangest stuff you've got.

I'm late to the party, but what's new?I see a lot of weird stuff in my travels, but what strikes me isn't so much the geology, but our weird response to the geology. Can you look at the rock in the picture at the beginning of the post and not see the face of monster trying to emerge from the ground? The rock results from a random process of weathering and erosion, but see it from the right angle, and the rock becomes of mythical story of beasts and human nightmares and heroes on quests. Perseus fought Medusa, who turned men to stone. Tree molds in Hawaiian lava flows were people turned to stone (above). The volcanic necks of the Four Corners region were the monsters who were vanquished by the Navajo Twins Monster Slayer and Child-Born-of-Water (below).Pareidolia is a psychological phenomenon "involving a vague and random stimulus (often an image or sound) being perceived as significant. Common examples include seeing images of animals or faces in clouds, the man in the moon or the Moon rabbit, and hearing hidden messages on records played in reverse". It's part of being human, the recognition of human faces being one of the most important skills of a newborn baby.

Of course, such things can get out of hand when we start seeing Jesus on tortillas, or faces on Mars that are obviously signs of Martian civilization (I thought it was Elvis myself). Or the Devil smiling in the smoke and ash of the Twin Towers burning (wasn't there enough evil in the hearts of the terrorists?).

What's Eating the Joshua Trees? What's Not Eating Them?

For some reason, the powers-that-be somehow failed to call the incredible geological desert in Southern California "Great Big Granite Boulders National Park". They called it "Joshua Tree National Park" instead. I don't quite understand, but that's the way things go sometimes. Really though, the bizarre little 'trees' have a geological history, and it may be their undoing.
The Joshua Tree is actually a member of the yucca family (Yucca brevifolia, meaning short-leaved yucca), and is so closely associated with the Mohave Desert that the boundaries of the one practically coincide with the other. The "trees" grow to a height of 35-40 feet, and are a centerpiece of the Mojave ecosystem, as many animals shelter within the tree and underneath it. The trees have a symbiotic relationship with the Yucca Moth, in which the moth is pretty much the only organism that pollenizes the flowers, and the larvae of the moth pretty much eat only the seeds of the Joshua Tree.
The iconic trees of Joshua Tree National Park are threatened, and as is often the case, we have met the enemy, and he is us. Human generated global warming is raising temperatures in the California Desert, just as it is everywhere else. Joshua Trees are sensitive to such climate change and are no longer propagating in the hotter areas of the park. As the climate warms, more and more trees in the lower edges of the desert will disappear. Normally they would propagate in higher cooler parts of the park, but there is a complication...the problem is a load of crap, or more properly a bunch of dung that is no longer being made.
Today, the only animal that transports Joshua Tree seeds is the woodrat, but they don't move much more than a 100-150 feet from the trees. That's not far enough to get the seeds to higher, cooler elevations, and so there is a possibility that within 50-100 years, most of the Joshua Trees will be gone from Joshua Tree National Park, just as the glaciers will be gone from Glacier National Park. There will be places at the north edge of their range where they will be able to survive, but they may have trouble getting there without human assistance.

So how did the trees get around in the past? That's where the dung comes in (or out...). It seems that we have discovered the droppings of giant ground sloths which once lived all across the southwest. It seems odd that we would have examples of their, uh, reprocessed food, but some of them favored dry caves and there are lots of samples to work with. And they contain a lot of Joshua Tree seeds and leaves. It is pretty clear that sloths provided mobility to the seeds of the Joshua Tree, and when they went extinct 12,000-13,000 years ago, the range of the Joshua Tree began to decline during the climate disturbances in subsequent Holocene time.
The picture above is a Harlan's Ground Sloth on exhibit at the Fossil Discovery Center near Madera in Central California. Despite the ferocious looking claws, it was probably a rather peaceful creature. I just hate that we cannot witness the wonderful menagerie of creatures that lived in North America just a few thousand years ago, although a few were probably the stuff of human nightmares (a future blog on this will be forthcoming). It occurs to me that instead of having humans simply plant Joshua Trees to insure their survival, we should be following a more logical solution. Doesn't it make more sense to use the DNA of the sloths to reproduce new sloths a la "Jurassic Park", and then release them into the wild to do the work that they were meant to do? How hard could it be, really?

For more info on the Joshua Tree and climate change problem check out this NPR story.

Water in a Dry Land: Joshua Tree National Park, and Getting Tanked

A lake in the desert? That can't be right...

Joshua Tree National Park has a bit of a schizophrenic aspect. Geologicially, the park is divided into vast tracts of metamorphic rock separated from large areas of granitic rock. Topographically, the park is divided into the higher Mojave Desert and the lower Colorado Desert (the High Desert and Low Desert of SoCal weather reports). The elevation and rock differences result in large contrasts in water availability, and thus vegetation; the iconic Joshua Tree is not found in the lower parts of the park, for instance.

The higher parts of the park exceed 3,500 feet, and the climate is cooler and wetter ("wetter" being a relative term), and this higher elevation desert even receives the occasional snow flurry in winter. My vivid memory of January camping at Joshua Tree as a Boy Scout was that of coldness, absolute extreme cold (probably merely close to freezing, but I was a southern Californian; we panic when the temperature drops below 50 degrees).

There's more water in the high desert, enough that the landscape could almost be classed as savanna. These higher elevations supported enough grass that a few ranchers scratched out a living in the region. Cattle need water, but the water doesn't flow at the surface much of anywhere in the park. The ranchers built a few small dams in scattered drainages to catch the runoff from rare rainstorms. These so-called tanks were of varying quality, and some have fallen into such disrepair that they no longer hold water, but others survive. One of the nicer (and popular) short hikes in the park visits Barker Dam in the Wonderland of Rocks area. We had a pleasant stroll there last week, on a sparkling clear day.

With a bit of revegetation effort and pathway control, one can see how grasses could almost support a cow, although the measure would be acres per cow rather than cows per acre. The grazing no doubt put severe pressure on the local population of bighorn sheep, who are occasionally seen in the vicinity of the reservoir.

The trail winds past some unique desert oak trees and a variety of yucca called Parry Nolina, which blooms into the showy stalks seen in the picture above. The bedrock in the area is entirely composed of a variety of granite called monzogranite, which formed deep underground as magma, and cooled slowly to produce the crystal-rich rock. As the granitic rock was exposed at the surface, expansion and stresses caused the rock to fracture along joints which became the focal point of weathering and erosion. The boulders weather more readily at corners and edges, giving them a rounded aspect. The process is called spheroidal weathering.

Closer to the dam, the rock is less jointed, and breaks mostly parallel to the surface, forming a dome-like structure, which is a relatively rare sight at Joshua Tree, and more familiar in places like the Sierra Nevada. This is the process of exfoliation (below).

The little reservoir captures the rare runoff from thunderstorms, and the resulting lake attracts all manner of birds, insects, mammals and other creatures, including tourists.

A look at the dam reveals what probably amounts to a lack of sophisticated dam engineering, but it has lasted for more than sixty years.

The area downstream of the dam is a beautiful landscape of rock and vegetation. A number of petroglyphs and pictographs (some unfortunately recent) can be found hidden in these rocks. The ranchers had probably built on top of a natural reservoir in the rock, and the area has been a source of water for a long time.

So what about these Joshua Trees? Is there anything geological about them? That will be next time...

Water in a Dry Land: Joshua Tree National Park, and why Twentynine Palms is missing a few

It is, of course, a cliche to say that water is life. I can barely imagine a more terrifying thought than to be trapped in the open in a place like the Pinto Basin in Joshua Tree National Park (above) on a scorching hot summer day without a car, without a phone (no coverage anyway), and without water. The Pinto Basin is the rarely visited wilderness end of Joshua Tree National Park, a place far removed from the famous granite boulders of Wonderland of Rocks or Hidden Valley. The Pinto Basin is a vast alluvial plain crossed by two old dirt tracks leading to abandoned mines, and nothing else.

The Pinto Basin was never developed like other desert basins in California because of a lack of available water resources and the arrival of the Great Depression just as speculators were moving into the region. The establishment of the monument sealed the deal and protected the wide basin from any more development.

It wasn't always like this. Studies at Joshua Tree have established that the region was more tropical for millions of years, and that during the Ice Ages a stream flowed through the valley. It was a place where humans could thrive instead of simply surviving. Archaeological work has established the presence of a people (the Pinto Culture) that lived in the basin from around 9,000 to 2,000 years ago.
Water is precious in the desert, and there are precious few sources there today. Ironically, the source of the water that is there is the same as the water the Pinto People used thousands of years ago. The gravels of desert basins like the Pinto act like giant sponges, storing water in the spaces between sand grains in the thousands of feet of loose sediment filling the valleys. Billions of gallons of Ice Age water remain hidden deep in the sediments, revealed only when geological conditions force water to the surface.

California has her faults, and faults are one of the ways that water can be forced to the surface. The grinding along fault zones produces a clay-like material called gouge, which is impermeable to water. Water flowing slowly underground can be dammed by fault gouge and forced to the surface. I visited two of those spots last week.

The first is Cottonwood Springs at the less-visited south end of the park (picture above). Water still flows there, but only a trickle. During the mining era, some 3,000 gallons a day provided the only secure water source for many miles around. The palms were planted in the 1920s (though they are a native species). The cottonwoods were present earlier. Water has been present here for thousands of years, indicated not only by Native American grinding holes in the rock, but also from travertine-like rocks in the area, deposited by water over tens of thousands of years. Needless to say (but I always say such things anyway), the water attracts a wide variety of animal and insect life.

The second "spring" we visited was the Oasis of Mara in an outlier of the park that serves as park headquarters in Twentynine Palms. Early miners called the oasis "Twentynine Palms Oasis", but the present name is a derivation of the Native American name for the spot. The oasis is marked by a line of fan palms along a recently formed scarp formed by the active Pinto Mountain fault (visible in the picture above). I was fascinated by the beautiful little pond in the midst of the healthiest looking fan palms, but I soon realized it was lined with plastic. A bit of research (like reading signs on the nature trail!) revealed that the springs of the Oasis of Mara have been dry for decades. It's not too hard to figure out why. The presence of water led to the establishment of the town of Twentynine Palms, and the town residents started drilling wells right away, drawing down the groundwater table and and drying up the springs. I'm not sure there are actually 29 living palms left today.

The last source of water we saw was a lake, of all things, hidden among the granite boulders. That's a unique Joshua Tree story for another post.

I've used three sources of information about the park beyond my own observations:

Cates, Robert, 1995, Joshua Tree National Park: A Visitor's Guide, Live Oak Press, 100 pages.

Trent, D. and Hazlett, R., 2002, Joshua Tree National Park Geology, Joshua Tree National Park Association, 64 pages.

Eggers, M, editor, 2004, Mining History and Geology of National Park, San Diego Association of Geologists, c/o Sunbelt Publications, 119 pages.

Taking Granite for Granted? Looking at Gneiss Rocks in Joshua Tree

Where can one find the oldest rocks in California? And for that matter, any place west of Utah and Wyoming? Some well-seasoned geological travelers would point to the bottom of the Grand Canyon, where dark metamorphic gness and schist lie exposed below the Great Unconformity. Others might point to the Black Mountains in Death Valley National Park, where similar rocks are exposed along the unique turtleback faults of the deep graben that forms the main axis of the park. These beautiful rocks formed during a collisional event (really two) between 1.65-1.75 billion years ago that formed a huge mountain range that extended across the southern part of the North American continent for an unknown distance westward. At the time, most of the continents of the world were combined into a supercontinent called Rodinia (which existed prior to the better-known Pangea).
If one takes granite for granted, as I did once at Joshua Tree National Park, one might miss one of the unexpected pleasures of exploring the park. The giant granite boulders in the Wonderland of Rocks may catch most of the attention, but there are secrets in the somewhat bland looking hills in the south and central parts of the park: the oldest rocks in the state! The Pinto gneiss and related rocks in Joshua Tree are related to those seen at Grand Canyon and Death Valley. These are the ancient metamorphic rocks that the granitic magmas invaded. These rocks once may have been sands on a beach some 2 billion years ago, or muds on a sea floor. Some may have been volcanic flows. All have been baked by the molten rock and squeezed into their present shape.
South of Cottonwood Springs at the less-used park entrance near Chiriaco Summit out of Indio, a desert gully along the park road exposes the contact zone between the granite and the gneiss (pronounced 'nice'). The contact is marked by an intrusion breccia, bits and pieces of the metamorphic rocks enveloped in the granitic rock. The isolated chunks of metamorphic rock are called xenoliths ('alien rock').
A hike to the Mastodon Mine out of Cottonwood Springs reveals one of the most unique exposures of xenoliths (or enclaves, see comments below) that I have ever come across. The metamorphic rocks are weathering differently than the granitic rock, and end up protruding like chocolate chips in cookie dough!
Joshua Tree National Park is a fascinating treasure. The story shall continue....

Taking Granite for Granted? Quick, Name a National Park in California!

Quick, name a national park in California...

Which ones appeared first in your mind? Yosemite? Sequoia? Maybe Death Valley? There are a few others, depending where you live, so Channel Islands, Redwood, or Lassen Volcanic might have been a first response. But who among you thought first of Joshua Tree National Park?

As a native-born and bred Southern California, I am guilty of ignoring the treasure that existed in my backyard. National monuments often get short shrift as part of our nation's national park system, and I am not totally sure why. Many people don't even know the difference, but somehow assume that monuments are somehow a second-tier series of parks, places that are almost as good as national parks, but not quite. Under law, national monuments are the equivalent of national parks, but monuments are declared by Presidents under the terms of the National Antiquities Act, and national parks can only be established by Congress. What this has meant in practice is that Congress has often been reticent about establishing national parks, given the many pressures exerted by special interest groups and lobbyists. Presidents, acting as a representative of all the people in the country, have recognized the national value and significance of these sites, and have declared them to be national monuments to provide protection of the resource.

Often, when a national monument has been in existence for a few years or decades, Congress finally comes around and establishes the monument as a national park. This is true even for some of our most iconic parks; both Grand Canyon and Zion were first declared national monuments before Congress acted in 1919 to make them national parks. There are numerous other examples.

So, why am I talking about national monuments? Joshua Tree is a national park. It turns out, though, that Joshua Tree followed a similar arc of many other park areas around the country. It was established as a national monument by FDR in the 1930s, and still was a monument when I was growing up in SoCal in the 60s and 70s. And I was guilty of thinking of monuments as second-class parks. When I dreamed of traveling, my heart was up in the Sierra Nevada somewhere, and I really didn't get to know Joshua Tree all that well, my trips being mostly confined to a handful of scout camping trips. I remembered a lot of big boulders, joshua trees, and vicious jumping cholla.

Joshua Tree achieved status as a national park in 1994, along with Death Valley, another longtime national monument. And I was by then living elsewhere. These last few years I have been working to rediscover some of these places of my youth that I took for granted. So I made a trip out there last week to check things out and found out that I was also taking the park for granite, too.

What did I learn? The first thing was an eye-popper...having thought the park was made entirely of granitic boulders, I didn't know about the rich variety of other rocks found there, and how they relate to each other. The picture above is one of the starkest examples. Click on it and enjoy a unique panorama; you are looking at a scene from miles within the crust of the earth. This is the roof of a granitic magma chamber, where it was intruding into the surrounding older rocks. Yosemite is famous for its exposures of granitic rock, but you can't see stuff like this in the Sierra. Once I saw this exposure, I knew we were in for an interesting day! More to follow...