Researcher
Profile: Andrew Valdez Researcher
Profile: Andrew Valdez What are the main things that you study?
At Great Sand Dunes five geologic processes have been identified that contribute to the formation of the dune system and I focus my studies on those processes to better understand them. Those processes are: rifting (the slow pulling apart of the earth's crust), wind transport of sand, stream transport of sand, the amount of vegetation growing on the sand, and the position of groundwater. Some of these studies are conducted by myself while others are done by other scientists with more expertise on the subject matter.
Here's what we have learned:
Rifting or the slow pulling apart of the earth's crust is what has created the nearby San Luis Valley and Sangre de Cristo Mountains. That is important to the dunes because it creates the setting for the dunes to form. As the crust is splitting, it breaks into blocks. Some blocks rotate downward, forming the San Luis Valley while others rotate upward forming the Sangre de Cristo Mountains. Since the valley is sinking, it is depositional (meaning that debris from the surrounding mountains is collecting there.) That debris includes sand which ultimately ends up in the dunes. Other Colorado valleys, such as the upper Arkansas River Valley, are erosional (meaning all the sand gets washed out) and sand dunes don't have the opportunity to form there. The mountains are important because of how they affect the wind patterns. We study rifting by examining the materials penetrated by deep wells, bouncing energy waves off of deep rock layers, trenching earthquake faults, and installing seismographs.
Wind transport of sand is important because it creates the dunes and controls dune behavior. If the wind blows sand over the dune in one direction, the dune will migrate over time and it will be relatively small. If the wind blows sand toward the dune from 2 or more directions it will tend to stay in the same area and get taller over time. We study the wind by using wind gauges and by measuring sand movement.
Streams that flow around the perimeter of Great Sand Dunes affect the edges of the dunefield. The large eastern face of the dunefield exists because Medano Creek eroded into the dunefield. The large southern face of the dunes is built from sand supplied by Medano Creek. Edges of the dunefield that do not border a creek have much smaller dunes. We study streamflow by measuring how much water flows in the stream, how far it flows, and how much sand it carries.
How did you get interested in this type of work?
I grew up spending lots of time in mountains and I loved to explore them. I wondered how the mountains formed and I would often break rocks to see what they looked like on the inside. In high school my favorite subjects were math and science. When I was a senior, a teacher asked me what I was going to major in, in college. I didn't know and she asked me what I was interested in. I told her about my interest in mountains. She suggested geology. I had never heard of geology prior to that. I took her advice and the rest is history. Thank you, Mrs. Fuji! Had I not heard about geology, I probably would have gone into the computer industry or perhaps some sort of engineering.
What is your favorite thing about your research?
I love to learn new things. This includes things that my research shows me and learning from other researchers. For example, we have wells with datapods that frequently measure the water level in the well. Once or twice a year I visit the well and download the data. When I get back to the office, I analyze the data and sometimes some really neat and unexpected information shows up. This data helps us understand the nature of ground water levels from day to day and year to year. It also shows how stream flow, precipitation, and droughts can affect groundwater. We collect data on many different things ranging from air quality, to weather, to dune movement, to stream flow, and much more. When you are managing an area like Great Sand Dunes, there is no substitute for understanding your resources and having good data helps us do that.