Final Post

The Physical Processes

Valley of Fire national park formed as part of the Cretaceous period which contributed vast quantities of sediment deposited in the region. For millions of years the area, covered by a vast shallow seaway, transitioned the landscape in unimaginably dramatic ways. Transforming a vast continental expanse into a great sea does not happen overnight and neither does recovery from such an event. Scattered across the southwest is evidence of this seaway from fossil records to sedimentary deposits. These deposits, interpreted by the science of stratigraphy, offers a glimpse into the timeline of the region and offers a way for scientists today to tell the story of how this great seaway would later lead to the formation of a great desert and the formation of vast sand dunes. After many more millions of years these sandiness lifted and froze in time. Now the red sand of history stands frozen in this small valley as a stark contrast to the dark uplifted stone in the background.

Source: http://pi.b5z.net/i/u/1248569/i/vof4.jpg 

Valley of Fire - 1,000 years from present
     The national park 1,000 years from now will look much the same as it does with the naked eye.  Assuming the Las Vegas area continues to expand the park may find itself inundated with human presence. Humans typically alter the landscape by planting invasive species and building monoculture patches whether for food or aesthetics. This incursion will likley raise humidity and increase erosion. The large sandstone formations will continue to fracture and weather as it has for millions of years, though the process is slow and the overall landscape should retain the majority of its physical characteristics. Nearby lake Powell will most likely be drained leaving behind the beginnings of a salt flat basin.

Housing development in Las Vegas expanding outwards towards the hills. Humans have a dramatic impact on thier environment and cannot be ignored in understanding the fate of landforms when looking towards the future. With recklass disregard for future generations new settlements into the national park will strip the region of its natural resources and provide the platform from which great urban centers are built. Image Source: http://www.carriagetrade.org/local/cache-vignettes/L550xH368/_4Alex_MacLean___Las_Vegas__Nevada-d1333.jpg

Valley of Fire - 10,000 years from present
    As humanity has most likely completely overrun the area and begun excavation and mining projects which flatten the landscape only a few solitary lithified dunes remain. The humans have some recoded history that this area was once a valued national park with petroglyphs dating back to early humans but most of this knowledge has been lost. Some seismic activity has shifted the ground but for the most part not major changes are noticeable.

The human cities introduce water pools, irrigation, industrial rivers and farmland all of which contribute to the new more humid climate and proliferation of new invasive species. This picture illustrates increased plant growth and darker, more fertile soils. Source: http://astrosun2.astro.cornell.edu/~randerson/Arizona09/IMG_0984.jpg

Valley of Fire - 1,000,000 years from present
     The human population has by this time been extinguished and the landscape looks very different.  After a millions years of weathering and erosion the sandstone edifices of the rocky mountain range have begun subsiding, dissolving into the Earth. This once arid landscape has entered a new tropical classification with the rising temperatures and humidity as the once frigid dry air masses from the north now descend with warm, wet air. The deposition from the ancient landscapes that came before now offer rich, fertile soil for a new tropical ecosystem to thrive with new and exciting forms of life. Rivers now running through the ancient national park carry away millions of years of depositional sediment from the cretaceous and down into the Pacific Ocean.

Humans are no more but the vestiges of thier ancient civilization persist if only for a little while longer. Source: http://www.history.com/images/media/slideshow/life-after-people-season-one/life-after-people-los-angeles-highway.jpg

New tropical land scape with ancient uplifted peaks now covered in plant life. Image source: http://hd.wallpaperswide.com/thumbs/waterfall_in_tropical_forest-t2.jpg

Weather and Water

The landscape of the Valley of Fire is striking in contrast to the surrounding landscape. The national park is situated in the area of the Mojave dessert and the predominant vegetation offered is only shrubs and small cacti.  The red hue of the park stands out against this bleak and monochromatic display. As described in previous entries, the morphology of the area suggests a sedimentary origin from an ancestral  Lake Mead.

Lake Mead -- Source:http://www.ens-newswire.com/ens/feb2008/

Situated in a rain shadow from the Sierra Nevada, Valley of Fire and the Mojave desert receive very little rain totaling only around 13in per year. During the winter in the national park the tempterature can dip to 20˚F and in some cases, in valley floors, as low as 0˚F. By contrast the summer days can reach temperatures as high as 130˚F. As demonstrated in the table above, the combination of solar new and the quantity of daylight throughout a 24 hour period will determine the temperature in some cases. In the case of the Valley of Fire the temperature change is exacerbated by continentality, which is the low latent heat capacity of land versus water.

Source: http://apollo.lsc.vsc.edu/classes/met130/notes/chapter3/daily_trend4.html

Large temperature variation makes strong winds common in the area which become the principle force for the creating of sand dunes and infertile, dry soils. These extreme temperatures will often result in the desiccation of the soil leading to geometric patterns in the earth as the moisture leaves and the volume of earth diminishes.

The close proximity to the Sheep Range of mountains offers spledid views of a type of cloud known as altocumulus lenticularis. These breathtaking clouds form of the peak of clouds resulting from orographic lifting. Wind then sweeps them eastward away from their birthplace towards Lake Mead and the Valley of Fire.

Lenticularis -- Source: http://www.flickr.com/photos/photomason/2453450456/sizes/l/in/set-72157604806059249/ 

Rock Decay

Rock decay is the principle mechanism which has shaped the present day configuration of Valley of Fire park. Without weathering, rocks would maintain their original appearance and location without any natural weathering processes to act upon them. Independent jointing in sandstone offers some of the first opportunity for infiltration by the forces of nature. As the exterior becomes vulnerable to water the process can begin. As water penetrates into the sandstone, the initial faults become more pronounced. Repeated freezing and thawing in these crevasses pushes the rock further apart.

A photo I took at the park showing countless faults forming in the sandstone.

Another feature of rock decay and weathering are these pools that form in the rock.  These are formed by a small depression filling with water. The water has small pebbles at the bottom. Wind blows the water and stirs it around which leads the pebbles to begin scraping away the rock around the edges.

Pool formed by wind, water, and time.

 
 In arid environments like the harsh Nevada landscape, continuous evaporation of available water, deposits load after load of salt molecules on the surface. The presence of these salts results in a type of rock decay that dominates these lithified sand dunes.

Salt weathering is a type of mechanical weathering which very slowly chips off pieces of the sandstone, one grain at a time. Previously believed to be the result of wind erosion, large holes in the rock (as seen in the picture below) developed by salt weathering represent some of the most iconic visuals of the park. Salt weathering however, does not begin by forming single large holes like the one I’m inside. Salt weathering, especially in sandstone, begins by forming small holes called alveoli. These tiny pits in the rock begin to expand and grow resulting in the formation of tafoni. After even greater periods of time as the salt continues to weather away the rock, resulting in the larger holes that a person cal climb into.

Tafoni forming in sandstone

Sources:
- http://digital-desert.com/valley-of-fire/index.html
- Pictures by Sam Epperly except for the tafoni picture which I found here: http://0.tqn.com/d/geology/1/0/4/I/1/voftafoni.jpg
- Slides from lectures

Physical Processes

The Valley of Fire is composed primarily of a sedimentary rock called sandstone. Great sand dunes 80 million years ago eventually settled and formed the hills that make up the area. Transform or slip-strike faults are responsible for the tectonic activity at the site. The mountains which typically appear in the backdrop of the valley of fire were created by the large thrust faults.

The red sand stone is exposed from a large arc fault known as the Sevier fold-thrust. The arc fault extends all the way up to Canada influencing much of the topography and landforms seen throughout the West. The sand dunes here which formed while the western interior seaway was still in existence and later transitioned from a marine bay to desert. The ancient desert that created these ancient sand dunes was large enough to span from Wyoming to Arizona.

As a sedimentary rock, sandstones present with dependent faulting which divide the rock surface into different strata. Over millions of years and through changes in atmospheric and climactic transitions, new strata is layered on top of old which facilitates the dimensions of time and help geologists understand that massive temporal scales that take place to create these formations. 

Despite the presence of thrust faults and creation of adjacent mountains in the backdrop, these tectonic processes may not have been responsible for the create of the valley of fire. The transition from sediment to sedimentary rock, known as diagenesis may, may have occurred before this faulting occurred. Indeed these sand dunes did find their origin at the coast of an ancient ocean and would have substantial time to transition into their current configuration. 

Sources:

- http://geology.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=geology&cdn=education&tm=80&f=00&su=p284.13.342.ip_&tt=33&bt=0&bts=0&zu=http%3A//3dparks.wr.usgs.gov/lame/html/lame_history.htm

- http://en.wikipedia.org/wiki/Valley_of_Fire_State_Park

- http://geology.about.com/od/geology_nv/ig/vofparknevada/

- https://pangea.stanford.edu/research/geomech/People/Flodin_diss.pdf

- http://geology.utah.gov/utahgeo/geo/thrustfault6.htm

Introduction to the Valley

Hello,
My name is Sam Epperly and I am studying Environmental Science as a, "one semester left!" senior. I am originally from Minneapolis, Minnesota and have always had a tremendous love for the natural sciences since as far back as I can remember. To that end I encouraged my family to leave our common destination for family vacations, Las Vegas, Nevada, and journey 50 miles to the northeast where we find the Valley of Fire. In this particular area of sedimentary sandstone deposition, a peculiar natural phenomenon stands out among the common yellow sandstone. What appears to be a raging fire in the distance, which can only be described in the eyes of a young explorer, as astonishing, transforms into a breath taking rock formation composed of relatively cool, and unthreatening clusters of red tinted sandstone.

When we finally managed to reach these impressive formations which stood hundreds of feet above my head, I would revel in no greater pleasure afforded by the simple excitement of climbing as high as I could without the assistance of ropes or proper climbing attire. In a matter of minutes I could reach the summit of these great geologic bodies and proclaim dominion over my newest conquest. This place holds special reverence in my mind and I will always remember the ignited passion for nature which took place there. I am excited and intrigued to learn about the natural processes which brought this sanctuary into existence and more than anything, to gain a new appreciation of its wonders.

Photo Citation: http://talkingtree.org/images/20090203100314_naturalarch.jpg