Stop 3: Ash Lens

A finger points to a layer of pinkish-colored rock embedded within layers of darker rock.
A lens of ash is seen within the surrounding sandstone.

NPS/Eric Grunwald

Quick Facts
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Scenic View/Photo Spot

Head down the trail about 45 feet from the second switchback. At this point if you look to the left side of the trail, you will notice the rock has a thin layer of pinkish-colored material embedded in it.

This is an "ash lens", also known as an "ash lentil". In geologic terms, a lentil or lens is body of ore or rock that is thick in the middle and thin at the edges, resembling a convex lens in cross-section. This ash lens can also be seen in the cliff face to the south. Note both the cross- and horizontally stratified sandstone above and below the ash. Volcanic ash is a major component of Scotts Bluff. In some places it is mixed with sandstone. In other locations, like here, it is found alone within layers of other rock. 

To continue the tour, head down the trail to the next stop, at the set of concrete stairs. So far the different layers of rock we have seen have been have been relatively horizontal. However, as you approach the stairs at the next stop on the tour, look for sandstone that shows evidence of cross-stratification. That means the layers are angled instead of horizontal. 

Scotts Bluff National Monument

Last updated: December 15, 2020