The Earth Story

Furnace Creek Formation This spot is just up the road from the temperature gauge that may have recorded the highest temperature ever measured by humans earlier this summer. This Panorama captures Zabriskie Point, an amazing, desolate landscape in the heart of Death Valley National Park. It’s a little hard to imagine, given the heat this year, but in fact all of the sediments you see in front of you were dropped down at the bottom of a lake.

Painting This photograph captures “Artist’s Palette” in Death Valley National Park in just about the right light to illuminate the features. Artists Palette sits on the edge of the Black Mountains, one of the ranges that surround Death Valley and create its unique microclimate. It can be accessed easily from the main park roads.

A day at the beach I love this site. As you drive into Death Valley from the southern access road, this small mound rises from the valley floor. It sits at the northern end of a series of hills and is bounded by faults on both sides, so it is basically just of a piece of rock that juts out into the basin that is Death Valley. The rocks are some of the many volcanic rocks that erupted on the valley floor as the faults moved and the valley split open, but the most famous feature on this slope is the series of nearly horizontal lines you can spot easily in this photograph.

Dune motion Sand dunes move due to wind. As air moves rapidly up the slope of a sand dune, it causes sand to saltate, bouncing upward with one grain hitting another until it reaches the crest of the dune. At the crest, sand piles up until the dune becomes too steep – the weight of the sand overcomes the frictional forces that hold the grains together. At that point, a small avalanche takes place – sand heads down the steep side of the dune, restoring the balance between friction and gravity. This shot of California’s Kelso Dunes captures a marvelous set of examples of this process; a series of sand grain avalanches, one after another, bringing material down from the crest of the dune. -JBB Image credit: http://bit.ly/1F6tmPl Read more: http://www.desertusa.com/geofacts/sanddune.html http://www.nps.gov/grsa/learn/nature/dune-types.htm

Original caption:

Arizona and California road trip. Original caption:

Summertime voyage through California, from the hot sand dunes of Death Valley to the high peaks of the Sierra Nevada

Ventifacts

This is a sand-polished rock on a location known as Ventifact Ridge in Death Valley. Ventifacts are the remnants of erosion by sand and wind. Winds can start sand saltating: bouncing across the surface of the Earth at elevations less than a meter.

Any rocks in that range will be hit by that bouncing sand. A single sand grain doesn’t do much, but if the winds are strong and constant in a single direction, over time the wind-blown sand will act like sandpaper or sandblasting. Even rocks will erode in the face of that wind.

These ventifacts are forming pits the rock. Sand is gathering in those low spots, concentrating erosion and digging the pits deeper. You can even see two different directions created as the straight-line winds maneuver their way around the surface of the rock.

-JBB

Image credit: http://commons.wikimedia.org/wiki/File:Ventifact_at_Ventifact_Ridge_in_Death_Valley_NP(3).JPG

Read more: http://www.ventifact.com/