Weather Phenomenon

  Death Valley displays many different types of weather phenomenon. Valley fog is a common type of fog (a cloud of water droplets that hangs near the Earth's surface) that occurs in Death Valley.

The low-lying cloud in the picture is an example of Valley Fog. Valley Fog occurs when the low-level moisture condenses and the colder air from the surrounding peaks pours down into the valley below, leaving an inversion layer of warm air above it. Photo credit: http://www.myjeeprocks.com

 
  Haboobs (or dust walls) often occur in desert-type regions such as Death Valley.

A Haboob like the one shown above is created by air from an approaching thunderstorm racing out ahead of the storm in a form and process called a gust front. Photo credit: http://www.kcet.org

  Dust devils are an interesting weather phenomenon involving a rapidly circulating column of air.

The dust devil can be seen left of center in the picture. Dust devils are created during periods of extreme surface heating, where hot air near the surface rises and hits cool lower pressure air above it, sometimes causing the air to rotate. Extreme suface heating occurs during a dust devil but the air fails to reach the LCL (Lifting Condensation Level). Photo credit: http://www.moonriverphotography.com 

  Lightning is a dangerous but beautiful weather phenomenon that is usually (but not always) created by cumulonimbus clouds (a thunderstorm cloud).

Lightning (like the one shown in the center of the picture above) begins with an electrical spark in the atmosphere. Negative and positive charges attract; the electrical spark that begins in the atmosphere moves towards the ground and toward an opposite charge in the form of a step leader. When the negative and positive charge connect, a conductive path is created from the cloud to the ground below, creating a bright flash of lightning (the visible stroke). In the center of the picture above, the bright flash of lightning is an example of a visible stroke where the negative charge connected with a positive charge below. Some of the fainter lines in the picture are examples of the negative charge in the cloud not finding a connection below. These remain so-called "invisible" strokes. Photo credit: http://www.superstock.com

  There are many different forms of lightning. One such forms of lightning is spider lightning.

The lightning shown at top center is an excellent example of spider lightning. Spider lightning travels a horizontal path and can sometimes travel tremendously long distances as a result. Photo credit: http://www.teamliquid.net

Weathering

  Death Valley is filled with countless examples of weathering. One way this process works significantly upon rocks is through joints (cracks or fractures in rock); joints speed up the process of weathering by allowing access to space within the rock for chemical and physical weathering to take place. An example of a rock with many joints and on-going physical weathering is pictured below.

The faint white coloring of salt along some of the joints in this rock (e.g. the white colored cracks in the shadowed portions of the rock towards the bottom right and bottom left of the photograph) are evidence of salt weathering, a typical kind of weathering in desert environments (click the photo to enlarge it). Photo credit: http://www.flickr.com/photos/7230309@N05/2657404804/

  Physical weathering in dry places like Death Valley often takes the form of salt weathering because there is insufficient moisture to wash away the accumulation of salts. The effect of salt weathering on rock can lead to a specific form and process called cavernous weathering. Two types of cavernous weathering are displayed in the following pictures.

The large, smooth, gaping, cave-like holes in this boulder are called Tafoni and they are the result of salt weathering. Photo credit: http://www.geog.le.ac.uk/staff/.

The small but distinct holes on the side of this rock are good examples of Alveoli and are also the result of salt weathering. Photo credit: www.portervillecollege.edu/.

 
  Another form and process of weathering that we can find in Death Valley is that of case hardening. Case hardening is a term used to describe rocks that have outer shells that are more resistant to erosion than what is beneath that external shell. The picture below illustrates the concept nicely.

The two egg-shaped boulders in the center of the photograph are examples of case hardening. The resistant outer layer (called a weathering rind) developed a rock varnish, which made it less vulnerable to erosion than the parts beneath it. Photo credit: http://avtanski.net/images/var/boulders.jpg

  In addition to physical weathering there is also the process of chemical weathering occuring in Death Valley. Spheroidal forms such as the ones pictured below result from a type of chemical weathering called spheroidal weathering.

Spheroidal forms are produced when chemical weathering first begins on the corner of rocks. When this happens, the rock takes on a spheroidal shape. As erosion wears down the surrounding material, the rocks become exposed to the surface and we are left with a collection of boulders such as the ones in this picture. Photo credit: http://jennifercutler.com.

 
  In arid desert environments such as Death Valley, chemical weathering can profoundly effect granite by the process of biotite weathering.

This rock shows advanced erosion through biotite weathering, which is a specific type of chemical weathering process that involves oxidation. Biotite weathering has eroded the granite to such an extent that the surrounding ground has accumulated a large amount of small pieces of coarse granular sand. This granite sand (visible on the ground in the photograph) is called grus. Photo credit: http://portervillecollege.edu/

The landscapes of Death Valley are abundant with examples of faulting. The picture below is of the Furnace Creek Badlands in Death Valley. The mountains are marked with what is called normal faulting by extension. Extension occurs when the stress being applied to the rock is in opposite directions and pulls apart the rock. The process of extension leads to a form and process called stretching. Eventually the rock can break under this stress to create normal faults by extension. The many triangular facets along the sides of the mountains and the wine glass valleys forming along the base of the mountains are forms in which the process of faulting by extension manifests itself.

                                               Photo Credit: http://library.byways.org/

This particular mountain below possesses numerous examples of diastrophism all along its surface. The thick white layer running along the side shows folding. Its folding comes in the form of anticlines (convex bends upward) and synclines (concave bends in a depression). This was accomplished through stresses being applied against each other from opposite sides. This type of process is called compression and it can lead to the rock deforming in the manner of folding.

                                                     Photo Credit: http://www.pitt.edu/

Towards the right side of the mountain, the white layer of rock breaks cleanly only to continue above unconnected. This would be an example of strike-slip faulting left lateral. More towards the center of the mountain there appears to be a strike-slip fault in the right lateral direction. Strike-slip faults are created by side by side lateral stress (from the perspective of looking along the layer) in opposite directions; this process (called shearing) warps and deforms the rock horizontally (from the perspective of looking along the layer), which can lead to the strike-slip faults shown above.

Introduction

This blog is created and maintained by Anthony Cordova.

   I am Anthony Cordova, a Senior undergraduate Philosophy student at the University of Colorado at Denver. I have chosen as the subject of this blog Death Valley California, the hottest place in North America. Ever since I was a boy I have had a perverse curiosity and interest in inhospitable places. I think this has to do with the hard and austere resourcefulness that I feel life must possess in such harsh places in order to succeed. It seems to me that in these places especially we see very interesting and unique adaptations from life on display.

   But there are other reasons for my interest in Death Valley California. Several years ago I did some reading on this location and I learned many things about it that challenged my view of what it was. Contrary to my original erroneous understanding, there is a lot more geographical diversity there than I had assumed, from sand dunes to endorheic basins, salt crystal fields to extensive underground cave networks, marbled canyons to small waterfalls and ever so much more besides. The truth is, Death Valley is rich and diverse in geographical features; there is much more to it than just the insufferable heat and low elevation. I have wanted to visit Death Valley for many years now. Although I had not planned for it, there is the opportunity now (through my effort in this class) to eventually visit as a geographically informed person, and to come away from a visit to Death Valley with a more meaningful experience than I could have had otherwise.