The Universe Truly IS in a Grain of Sand

          You may have noticed I've been a bit sand-obsessed since my trip to Great Sand Dunes National Park in Colorado in October. Discovering these individual sand grain images magnified 250 times has blown in a fresh look at sand. The sea urchin spines in the right part of the image are particularly striking in this calcium carbonate-rich sand:

      The three-pronged sponge spicule in this image from a Maui beach is but one sand grain; "sand" is defined as a size of sedimentary particle ranging from 1/16 to 2 mm, rather than composition (I.e., quartz).

     Sand grains may also be glacially deposited as these grains of garnet, agate, epidote, quartz, magnetite, and hematite, in Lake Winnibigoshish, WI.

      Sand grains of gypsum from the White Sands area in New Mexico, are some of the most uniform in color, though they are quite soft (hardness of 2 on Moh's Hardness Scale):

      And the hydraulic fracturing sands in western and southern Wisconsin are quite uniform, hard (hardness of 7 on Moh's Hardness Scale) quartz grains:

      "Puffy stars," calcium carbonate forams on Okinawa beaches are quite uniform in size and have a distinctive shape:

     Note the rounded, smooth shells, foraminifera, piece of coral, and the volcanic fragment (in the lower right.)

     Check out these colorful, luminescent, rounded bits of foraminifera, shells, and quartz in this sand mix.

And, to tie things back to where we started this week, here are rounded, smoothed, sea urchin sand fragments from Hawai'ian sand; these are essentially cross sections of the long, green spines seen in the first image.

Take this all with a grain of calcium car- bonate or quartz or gypsum salt or. . .

Steph

There are GLOSTA lovers in Colorado!

Great Sand Dunes National Park: Kinky Dunes and Funky Surges

     Great Sand Dunes National Park in Colorado is home to breath-taking 750-foot tall sand dunes, the tallest sand dunes in North America.

       The ever-changing dune field is nestled up against a kink in the Sangre de Cristo Mountain range just east of the dunes and covers over 30 square miles.

      It is also home to the pulsing or surging Medano Creek which flows in the spring. The surge feature is a unique hydrologic phenomenon seen in this two-minute video. The National Park Service describes the connection between water, sand, and slope causing the surging flow as being akin to ocean waves. This excellent link on surge features describes Medano Creek and other surface creeks and the underlying water table as similar to the circulatory system of the human body.

     The 150,000 acre dune field is also home to the Tiger beetle, found only at the Great Sand Dunes.

         The San Luis Valley graben that contains the park (and the adjacent horst that includes Mt. Zwischen) is one of the northernmost reaches of extensional Basin and Range  that dominates the state of Nevada. The San Juan mountains border the graben to the west.

      In 1807, Zebulon Pike described the dunes, "Their appearance was exactly that of a sea in a storm (except as to color), not the least sign of vegetation existing thereon."

      Streams and creeks flowing out of the San Juan Mountains to the west over millennia carried gravel and sand into shallow lakes or sabkhas (salt flats) in the San Luis Valley. 

       During drought periods, these lakes dried, releasing the sand particles to the action of the wind. Strong prevailing southwesterly winds carry the tiny grains toward the Sangre de Cristos, piling them up against the foothills. 

      Yes, in the name of science and PEOTS, Maizie and I will be traveling southward this week to report on the state of the dunes. (Yes, we sacrifice for this blog!)

     Have you been to the Great Sand Dunes? Before or after 2004 when it was elevated from National Monument to National Park status?

From the sand dunes ocean state,
Steph


Cattle guard sign just south of the Great Sand dunes (Everything is pristine and quiet at the dunes. . .)