13 June 2008

Sand Dunes!

Posted by Ryan Anderson

Greetings folks! I’ve been silent for a few days because I am in the midst of a lot of traveling. On Monday, Tuesday and Wednesday this week I was at a team meeting for the Mars Color Imager (MARCI) and Context Camera (CTX). Rather than spend a lot of time explaining what that means, I will do what I always do and link to the planetary society blog. My adviser Jim Bell is guest blogging over there while Emily is on vacation, and he explains MARCI and CTX very nicely.

After that meeting, Jim and I flew down to Denver, Colorado and met up with Briony and Melissa. We then drove all night to get to Alamosa. After a few hours of sleep, we met up with a couple of colleagues who are sand dune experts and headed out to Great Sand Dunes National Park and Preserve.

The dunes are situated in a flat basin, surrounded by mountains on all sides, and you can see them from a long way off as a series of buff-colored rises. As you drive closer, the dunes loom larger and larger. From twenty miles away, they look like you’re almost there, because any other dunes you’ve ever seen are smaller. The dune field at the park is enormous: the tallest dune is 750 feet (229 m) tall! When we finally arrived at the base of the dunes, this was the view:

(Click for a larger version and try to spot the people climbing the dunes like ants on an oversized anthill)

As you can see, there is a stream to cross before reaching the dunes. This stream acts as a conveyor belt for sand: the wind blows sand from the dunes into the stream, which washes the sand back upwind so it can be lifted by the wind and become part of the dunes again.

There is no word for these dunes other than spectacular. I could wax poetic all night about them, but instead, I’ll let a few pictures do the work for me:

The beautiful, lighter-toned ripples in this view are made from coarser, more quartz-rich sand grains than the surrounding dunes.

Here we are setting up a GPS station. To goal of the day’s field work was to use GPS to measure the shape of several dunes very precisely.

Blue sky, mountains, dunes. What this beautiful view doesn’t convey is the sandblasting that we received as the afternoon winds picked up.

And finally a panorama of the dunes, as seen from the visitor’s center in the afternoon light. Click for a much bigger version! Can you find the people in this picture?

Stay tuned, I’ll have more dune pictures tomorrow, and then we’re all heading up to Winnipeg Canada to visit some Mars-analog locations.