The Future of the Great Sand Dunes National Park

The Great Sand Dunes National Park and Preserve has certainly made a name for itself in the Geography world by being and extremely interesting piece of geographical landscape. As a brief description the geography of the Dunes is made up of a couple different geographical elements. The dunes are surrounded by two separate mountain ranges, the Sange De Cristo Mountain Range and the San Juan Mountain Range which were created by moving plates beneath the Earth’s surface. In between the mountain ranges is a large valley. Another geographical element at the dunes is the Medano Creek which serves as home to a larger hydrology system under the surface. The actual dunes are formed by specific wind patterns and are made of sand. There are also various types of dunes. All of these geographical factors have not only played a role in creating the dunes as we know them today, but are also responsible for the geographic future of the sand dunes.

Based on the geographical structure of the sand dunes and my knowledge in geography I can make educated guesses on what the dunes will look like in the future. In 1,000 years I suspect the dunes will not look much different than they do now. This is because the wind patterns seen around the dunes. These patterns balance each other out making the formation of the dunes rather consistent. Since the dunes have existed we have not seen many changes, but this is not saying that they do not change. Scientists have discovered many new things about the dunes even in just the recent future that proves the dunes do change over time.

In 10,000 years I think we will see a little bit of change in the Great Sand Dunes. I think that we will see a growth in the amount of dunes. This will be very slight, but I do think that it will occur because it is continuously occurring as we speak, slowly, but definitely.  I think this because of the vegetation that occurs along the dunes. Wind eventually erodes the vegetated dune, which as discussed in my previous blogs, this natural occurrence creates what are called parabolic dunes. These parabolic dunes eventually migrate into the main dune area creating more surface area of dunes for the future.

100,000 years in the future is when we will most likely see the most change. This is because any geographical process that occurs is typically a slow process. I believe a lot of vegetation will occur on the older dunes and that they will remain as they are because of the vegetation growth because vegetation on the large dunes typically stops them from migrating. However, there will certainly be more dunes than there are now because sand constantly is being carried to the dunes via wind and Medano Creek. Another reason we will not see a lot of major change is because the hydrology system of the dunes. The hydrology system consists of a high water table keeping the under layers of the dunes wet, making them more solid and heavy, keeping them in place.

Although the Great Sand Dunes definitely change on a daily basis, we as scientists and observers don’t get to see a lot of this change because it occurs very slowly over time. However change is a guarantee given the dunes geographical elements such as wind pattern, vegetation, and hydrology. It seems that change is held within the closed system of the Great Sand Dunes National Park, but that it will also keep occurring as long as the dunes exist.

Wind is the Reason for the Season

 Wind put simply is air in motion. Most people (including myself) dislike this geographical phenomenon, but in reality wind is extremely important to Earth's form and the way it works. Specifically, for the interest of the blog, wind is an extremely important to the formation and existence of the Great Sand Dunes National Park. As I discussed in an earlier blog, the Sand Dunes were formed in the San Luis Valley floor. Lake bed deposits were found by geologists within the valley floor in 2002. There were smaller lakes the covered the valley floor also, but with climate change these lakes disappeared, leaving behind a “sand sheet”. This is where the wind comes into play in forming the dunes. Predominant winds blow the sand towards the mountain range while wind during storms, or storm winds, blow the sand back towards the valley. The opposite blowing of these winds is what causes the dunes to grow as it piles the sand upwards. Wind is also the reason that different dune types occur within the park. Different wind types are what cause each of the different dune types. These types are reversing dunes, Chinese wall dunes, star dunes, parabolic dunes, barchan dunes, transverse dunes, and coppice dunes. I discussed earlier how reversing dunes are formed by predominant and storm winds. Chinese walls are what form on top of the reversing dunes. Parabolic Dunes are formed due to the type of vegetation growing in the sand. Barchan dunes are formed from winds that only blow in one direction. Coppice dunes are the dunes formed around large vegetation. Star dunes are formed by winds that blow from different directions over the course of a year.  An excellent animation that explains how different wind patterns form each of these different dunes types can be found here: http://www.nps.gov/grsa/naturescience/dune-types.htm. Although not always the most favorite climate phenomenon, wind is extremely important to the existence of the Great Sand Dunes National Park.

Hydrology and the Great Sand Dunes

From an untrained mind, The Great Sand Dunes National Park may not seem like a place in which hydrology is a main factor. However, from what I have learned in geography 1202, hydrology has a lot to do with the dunes existence. Typically, one may think that the sand dunes are home to an arid ecosystem where there is not much plant and animal life, but this is highly untrue. The water features are the whole reason plant and animal life exists at the dunes. Medano Creek, which I believe I mentioned in previous posts, may seem shallow on the surface, but it is actually just the top layer of a water system that exists below the surface. The sand dunes are home to a particularly high water table, which is the level to which water rises. The water that makes up the water table is what we consider groundwater which is water contained in the zone of aeration and the zone of saturation in a given area. Below the surface is also an aquifer, which is an underground layer of water containing materials (in this case I assume sand) in which ground water can be extracted and used. The Sand Dunes and surrounding mountain areas is hme to a recycled hydrology system in which the mountain creeks recycle capture sand, bring it to the valleys, where wind will then pick up and carry it to the dunes where it collects and piles, forming the gigantic dunes. A perfect example of why hydrology is so important to the duens and geography in general. The hydrology system is a huge factor in what created the dunes and is what maintains the dunes as we know them today!

 

 This picture serves as an explaination of the water table of the dunes and the aquifer that exists under Medano Creek. http://www.nps.gov/grsa/naturescience/hydrology.htm

So How Did They Get There?

        What first intrigued me about the Great Sand Dunes, was the fact that they seemed so out of place. Like I explained in my previous post, it just didn’t seem like the dunes belonged in the middle of the Rocky Mountains. Now that I am becoming slightly more familiar with geographical processes, there is more explanation as to why these seemingly random land forms exist. What I learned is that there are actually two different mountain ranges that surround the dunes. One is called the Sangre de Cristo mountain range and the other is the San Juan Mountain Range. These mountain ranges exist because the process of moving plates within the Earth’s surface. This is what we call plate tectonics. The specific plate process that created the mountain ranges is convergence, where the plates came together and the Earth’s surface came up and together to create the mountains. Between the ranges is what we call a valley which is the flat land between the mountain ranges. This valley is where the actual dunes are located. As we all know the dunes are formed from sand which was blown into the valley by wind. Specifically the type of rock that makes up each dune is sandstone which is a classic sedimentary rock. Now I know a little further as to why the dunes are there and about what the dunes are made up of specifically.

An Introduction

Hi,

My name is Sarah Pehrson and I am a Geography 1202 student for the fall semester at the University of Colorado located in Denver, Colorado. For my blog project I have chosen to analyze, through the eyes of a geographer, the area known as The Great Sand Dunes National Park. This park is located in my home state of Colorado which is one of the main reasons as to why I chose the particular area. For my project I wanted to choose an area that I have already been to. I visited the Great Sand Dunes for the first time in 2005, when I was fifteen years old. I thought it would be especially interesting to get to know an area I am already slightly familiar with from a geographic point of view because although I have visited, I know nothing about it geographically. I also considered the Sand Dunes because I know there has to be some really interesting history and science behind it due to the nature of the area. It always seemed crazy to me that in the middle of what seems like usual mountainous Colorado, there are just giant piles of sand. It is almost like they don’t belong, therefore, I have always been curious as to how they got there. I will allow this blog to serve as my reflection of finding out many new things about this already slightly familiar and nearby area that has always been a mystery to me!