South of Percha Box

geo walk 2 detail

The geologic ramble described here was for the purpose of gathering information on the Fusselman Dolomite (“Sf”) Formation which overlooks the Percha Box.  On the map above, the walk to the “Sf” site is shown as a white line, starting at the culverts under NM-152, east of Hillsboro.  The walk follows Warm Springs Wash to Percha Creek and then down stream to the entrance to the Percha Box.  At that point the route turns southeast up a well defined wash and then uphill (first southeast and then northeast).

geo walk two on geo map

Along the way there were stops at a “Mlv” (Lake Valley Limestone) geologic unit, a deposit of “Dp” (Percha Shale), a “Tvs” geologic unit (volcaniclastic deposit from the Oligocene), and finally the Fusselman Dolomite (“Sf”) unit on the top of the hills.  And a bit of blooming cactus, in this case Claret Cup growing on the top of an Mlv outcrop (shown on the map above).

There is a great deal of geology along this walk.  The photo key map, below right, shows the point where the following photographs were taken and the direction of the photograph.  In the descriptions of the photographs, links are to posts on the Natural Observer Blog which have already been published.

photo locator map for geo walk two

In the first photograph below, taken from “A”, we are looking back up Warm Springs Wash, in the area where it has opened back up.  “Om” is the Montoya Formation, “Oep” is the El Paso Formation, “LPzkf” is karst fill from the Cretaceous, “Tsf” is the Santa Fe Group predating the Palomas Formation from the Miocene, and “Qayr” is alluvium (middle Holocene to present).

The second photograph below was taken from location “B” and is of the Western Boundary Fault of the Animas Uplift.

The third photograph below was taken from location “C”, near the ruin of a small rock and adobe structure with well.  The units shown here have been discussed above, except for “Qay” which is alluvium from the middle to upper Holocene and “Qah” which is historic alluvium.

wash view one


C photo from geo walk 2

The last photograph in this series (below) was taken from location “D”.  The entrance to the Percha Box is shown on the right, the wash with Percha Shale is shown immediately ahead, and the Fusselman Dolomite unit is shown at the top of the ridge, center right.

Fusselman Dolomite location

But remember, there is more to life than geology, even when there has been pitifully little rain.


© Robert Barnes 2018-2020