An Incredible Spot in the Mojave Desert, the Hole in the Wall. You could see it for yourself this summer

Summer is coming soon. If you are casting about wondering what to do, how about the adventure of a lifetime? Our department is offering a dyad class, Geology 191/Anthropology 191, the Geology and Anthropology of the Colorado Plateau, and it is an incredible chance to check out some marvelous geology along our southwestern tier of states: California, Arizona, Colorado, Utah, and Nevada. I want to give you a bit of a preview of the kinds of places we will be visiting...

The Mojave National Preserve is one of our nation's newest parks (established in 1994). It was carved out from Bureau of Land Management lands in the eastern Mojave Desert, preserving one of the most awesome sand dune complexes in the country, the Kelso Dunes, a barren landscape of geologically recent volcanic cinder cones, one of the largest Joshua Tree forests in existence, and some of the highest mountain ranges in the Mojave Desert, with rocks as old as 1.7 billion years old, as ancient as those in the bottom of the Grand Canyon. The preserve also encompasses a California State Recreation Area, the Providence Mountains, and Mitchell Caverns, a unique limestone cave system. The caverns were closed during the recession, and then severely vandalized, but they have finally been reopened for visitation (see this Facebook page for updates).

One of the most interesting corners of the park is called Hole in the Wall, along with Banshee Canyon. We will be staying at the nearby campground our first night on the road on June 2. It is a wonderfully isolated spot, 25 miles off the main highway, and even farther from developments of any kind. It has some of the darkest night skies I've ever seen, and it is serenely quiet (except for crickets and coyote yowls).

The region is quite unlike other parts of the Mojave. Instead of deeply eroded mountain ranges and wide flat valleys, the area around Hole in the Wall is composed of mesas and plateaus that seem to share more in common with the Colorado Plateau province just to the east. But these mesas aren't like Arizona's either. They are composed not of sedimentary layers, but of volcanic tuff, rock derived from unimaginably huge volcanic explosions the likes of which modern humans have never experienced.

Twenty million years ago, the region was one of low relief, the result of tens of millions of years of erosion and relative stability. But conditions were changing as the crust was stretched and broken up into a series of tilted fault blocks. The release of pressure on the underlying mantle allowed partial melting to take place, and volcanic activity exploded across the region.

The first eruptions took place about 18.5 million years ago when the Peach Springs tuff coated the entire region from an eruption center near Oatman, Arizona. The eruption involved as much as 150 cubic miles (640 km³) of powdery white ash that was so hot that in many places it welded into solid rock as it landed.

Shortly afterward (in geologic terms anyway, as it was 700,000 years later), a second caldera developed. It was located even closer, in the adjacent Woods Mountains. The eruptive "crater", actually a collapse pit, was about 5-6 miles across, roughly similar in size to Crater Lake. Once again, all life was obliterated for hundreds of square miles as hot ash blanketed the landscape. The Wild Horse Mesa Tuff makes up most of the rock found at Hole in the Wall.

The strange holes that gave Hole in the Wall its name are called tafoni. Small differences in the degree of solidification or cementation cause depressions to form which end up staying wet longer, and the minerals decay into small fragments that can easily wash or blow away.

A short trail (1.5 miles) loops around Banshee Mountain and explores the best of the eroded tuff. Starting at the small visitor center, the trail drops through a rugged narrow canyon. There are some drop-offs, but rings have been attached to the canyon wall, making it a lot easier to climb up or down. Once past the narrows, the trail has a gentle gradient, and provides interesting views in all directions. There is a nice collection of petroglyphs on some of the boulders around the south end of the mountain.

If you want to visit this fascinating corner of the desert with us this June, please check out the previous post for details. We will be on the road for two weeks, and this will be only the first of many wonders that we will explore.

Dreams of Summer and Southwest Travels: Hole in the Wall, Mojave National Preserve

Christmas is over and suddenly the snow and blizzards aren't so fun any more. I find myself dreaming of warmer places and times, including a great journey we took last summer across the southwest with my students. Since my current travels are over until February, I'm going to travel through the archives to check out some marvelous geology along our southwestern tier of states: Arizona, New Mexico, Colorado, Utah, and Nevada. But really, no place is more southwestern than California, where we will start this journey.

The Mojave National Preserve is one of our nation's newest parks (established in 1994). It was carved out from Bureau of Land Management lands in the eastern Mojave Desert, preserving one of the most awesome sand dune complexes in the country, the Kelso Dunes, a barren landscape of geologically recent volcanic cinder cones, one of the largest Joshua Tree forests in existence, and some of the highest mountain ranges in the Mojave Desert, with rocks as old as 1.7 billion years old, as ancient as those in the bottom of the Grand Canyon. The preserve also encompasses a California State Recreation Area, the Providence Mountains, and Mitchell Caverns, a unique limestone cave system. The caverns were closed during the recession, and then severely vandalized, but there are hopes that they will reopen in 2016 (see this Facebook page for updates).

One of the most interesting corners of the park is called Hole in the Wall, along with Banshee Canyon. We stayed at the nearby campground our first night on the road. It is a wonderfully isolated spot, 25 miles off the main highway, and even farther from developments of any kind. It has some of the darkest night skies I've ever seen, and it is serenely quiet (except for crickets and coyote yowls).

The region is quite unlike other parts of the Mojave. Instead of deeply eroded mountain ranges and wide flat valleys, the area around Hole in the Wall is composed of mesas and plateaus that seem to share more in common with the Colorado Plateau province just to the east. But these mesas aren't like Arizona's either. They are composed not of sedimentary layers, but of volcanic tuff, rock derived from unimaginably huge volcanic explosions the likes of which modern humans have never experienced.

Twenty million years ago, the region was one of low relief, the result of tens of millions of years of erosion and relative stability. But conditions were changing as the crust was stretched and broken up into a series of tilted fault blocks. The release of pressure on the underlying mantle allowed partial melting to take place, and volcanic activity exploded across the region.

The first eruptions took place about 18.5 million years ago when the Peach Springs tuff coated the entire region from an eruption center near Oatman, Arizona. The eruption involved as much as 150 cubic miles (640 km³) of powdery white ash that was so hot that in many places it welded into solid rock as it landed.

Shortly afterward (in geologic terms, anyway, as it was 700,000 years later), a second caldera developed. It was located even closer, in the adjacent Woods Mountains. The eruptive "crater", actually a collapse pit, was about 5-6 miles across, roughly similar in size to Crater Lake. Once again, all life was obliterated for hundreds of square miles as hot ash blanketed the landscape. The Wild Horse Mesa Tuff makes up most of the rock found at Hole in the Wall.

The strange holes that gave Hole in the Wall its name are called tafoni. Small differences in the degree of solidification or cementation cause depressions to form which end up staying wet longer, and the minerals decay into small fragments that can easily wash or blow away.

A short trail (1.5 miles) loops around Banshee Mountain and explores the best of the eroded tuff. Starting at the small visitor center, the trail drops through a rugged narrow canyon. There are some drop-offs, but rings have been attached to the canyon wall, making it a lot easier to climb up or down. Once past the narrows, the trail has a gentle gradient, and provides interesting views in all directions. There is a nice collection of petroglyphs on some of the boulders around the south end of the mountain.

If you want to visit this fascinating corner of the desert, you'll have to search it out. It's not a quick roadside stop, but is instead a place to take a bit of time to explore. The time is well worth it!

The Abandoned Lands...A Journey Through the Colorado Plateau: A real Hole in the Wall

Some places can only be described as a real hole in the wall...this one for instance, in the Mojave National Preserve in Southern California. Also, may I add, we need state legislators like we need another hole in the head (more on this later).

It was the first morning camp of our trip. The previous day was spent going 450 miles, so our stops were limited to the open-pit borate mine at Boron, and the parking lot at Calico Ghost Town, the subject of the previous post. Today we would have the chance to explore a little bit. We had spent the night at the Black Canyon Group Campground at Hole in the Wall within the Mojave National Preserve, but had arrived in the dark and couldn't see much. We awoke at an ungodly hour since the sun was our alarm clock (I had no idea the sun was rising so early these days). In the space of an hour, our group of 34 people would need to pack their gear, load the vans, eat a quick breakfast, and prepare their lunch.

We quickly discovered that the cool morning hours were the best time for any kind of presentation. For some reason, brains steeped in 100 degree temperatures for 8 or 10 hours seem incapable of learning much of anything. Our anthropology professor talked about the Shoshone and Piute cultures of the eastern Mojave Desert at the Rings Trailhead (below).

We were beginning to realize that we were in a bizarre landscape. We were surrounded by strange tan and brown colored rocks with intricate holes and weathered surfaces. You wouldn't know it to look at it, but there is a deep crevice cutting through the rock cliff in the picture below. That is Banshee Canyon, where we would soon be walking. These rocks were clearly different than those that we had seen on our trip across the western Mojave Desert the previous day. There had been contorted sediments, red volcanic necks, and bouldery outcrops of granitic rock, but now we were looking at mesas and buttes of flat-lying rock with an unusual pattern of weathering. What's going on here?

I try to imagine things this way...it is 18.5 million years ago. You can put yourself in the picture if you want, but humans weren't around for this one; you might have been a camel ancestor, or a three-toed horse. You might have been a rhino ancestor, or an elephant. Maybe a predator like the Amphicyon "bear-dog". You've been living all your life on a savanna. One day there is something new happening...a cloud rises on the horizon, higher than any other ever seen. It is not noticed by the grazing animals, but the rumbles are; the ground is shaking and there is a vibration in the air. The animals startle and begin stampeding, but do not know which way the danger lies, so their movement is aimless.

Soon the danger is apparent. The hills to the east are covered by a rapidly moving ground-hugging cloud. The heat is not yet felt, but the sounds are heard. The animals try to escape to the west, but there is no escape; the cloud is moving at more than 100 miles per hour, faster than any animal can run. The animals are overwhelmed and incinerated. The entire landscape is buried a few hundred feet deep in powdery ash and chunks of rock carried along in the inferno. The rock was so hot as it landed that it hardened into solid rock immediately, becoming a welded tuff.

Unsensed by any of the now perished inhabitants of the region, a gigantic hole has just collapsed thirty or forty miles to the east. Something on the order of 100 cubic miles of rhyolite (silica-rich) ash has just exploded from the Earth's interior, leaving behind a circular caldera 10 to 12 miles wide.

In your mind anyway, you have just witnessed something that no modern human has ever seen, the eruption of a giant rhyolite caldera, a literal civilization ender. Similar eruptions produced the depressions at Yellowstone National Park, Jemez Caldera in New Mexico, and Long Valley Caldera at Mammoth Lakes, California. The layers of ash are called the Peach Springs tuff. Another way of understanding the scope of this eruption is to realize that the village of Peach Springs from which the tuff takes its name is about one hundred miles to the east.

A short trail winds through the tuff exposures. A few short climbs are necessary, and rings have been embedded in the rock to help out. It is a fascinating place to explore!

After a few minutes in the slot canyon, the trail breaks out onto the desert floor and circles the butte for a mile or so. This is high desert, and there is a wide variety of plants to identify (and in the case of the jumping cholla, carefully avoid!).

The weird cavernous weathering is called tafoni, and it is the strange holes that give the region its name. They arise from differential weathering of the tuff brought about by variations in the cementation of the tuff, and once started, by the continued presence of dew on the shadowed interior  of the holes after the sun has evaporated water on the outer surface of the rock.

The Hole in the Rock campground complex is our new favorite place to stay in this region. It was a nice discovery for us, brought about because of the irresponsibility of our California state legislators. Providence Mountains State Recreational Area is only a few miles away, with the beautiful jewel of Mitchell Caverns as a main attraction. It was the first casulty of the state's stupid policy of closing state parks instead of promoting them. There are some last second machinations going on to try and keep most of the parks open, but it is too late for Providence Mountains; the last two rangers retired, and expensive repairs to the water system were needed. They closed the park last year. They abandoned it, and the worst has already happened: vandals have done grevious damage to the park facilities.

Abandonment is to be a theme of this series, and it comes in many forms. It would take but a few pennies from each inhabitant of California to keep Mitchell Caverns open and viable as a park, but we've apparently left it to history. As we came around the last corner we saw an earlier form of abandonment, perhaps of an involuntary type: petroglyphs of the native Americans who once roamed the region in nomadic bands.

I noticed some dry blood on the rocks while I was in the slot canyon. I thought maybe an owl was a bit sloppy while consuming the night's catch, but when I got back to the parking area, I found that the blood actually belonged to one of my students. The day was getting complicated...

Here is the explanation of my "abandonment" theme for this series: http://geotripper.blogspot.com/2012/06/abandoned-landsa-journey-through.html