This page brings you on a virtual tour of our Geology Interpretive Trail (opened summer 2016), created by
Dr. Spencer Lucas, Director of Research and Collections at the
New Mexico Museum of Natural History and Science.
Use the information provided to get a better understanding of the geologic features and the history they tell of our part of the mountain.
A copy of the trail brochure can be downloaded at the bottom of this page,
as well as a paper further detailing SMNHC geology written by Dr. Spencer Lucas, et al.
Stop 1: Fossil Area
This area has cobbles of Pennsylvanian limestone full of fossils of marine animals – crinoids, brachiopods, bryozoans, corals, and sponges. These cobbles are loose deposits, not bedrock. The bedrock here is Triassic mudstone.
To learn more about animal fossils found here, download our Fossil Hunt Guide at the bottom of this page.
Stop 2: Glorieta-San Andres Contact
Stop 3: Oldest Bedrock
Reddish brown sandstone and siltstone (some with ripple marks) of the Permian Yeso Group are the oldest bedrock exposed on the SMNHC trails.
Thin section closeups of Yeso sandstone
Stop 4: Shark's Tooth
This block of limestone has a large tooth of the shark Petalodus. The block is loose and also contains brown nodules of chert, unlike any of the local Permian limestone bedrock. This is evidence that it is actually Pennsylvanian limestone which moved from a different location.
Stop 5: Glorieta Sandstone
The outcrop of Glorieta Sandstone here is about 10 meters of sandstone exposed along the canyon wall. This sandstone formed around 270 million years ago as part of a vast desert that covered part of the Southwest.
Stop 6: Paradise Benches
Limestones of the San Andres Formation exposed here were formed on muddy seafloors during the Early Permian. Above and below are Glorieta sandstones. The pattern of sandstone-limestone-sandstone-limestone records the march of desert (sandstone) and sea (limestone) back and forth over time on this landscape.
Stop 7: Strike Valley
Thin beds of reddish sandstone are river deposits of a vast Middle Triassic floodplain. These rocks of the Moenkopi Formation are softer than underlying sandstones and limestones and overlying sandstones and conglomerates. Thus, they form a “strike valley” between two ridges (cuestas).
Thin section closeup of Moenkopi sandstone
Stop 8: Overlook
The view to the north/northwest shows the basic geological structure of the SMNHC. The center sits near the base of the vast dipslope of the Sandia Mountains, which is underlain by Pennsylvanian limestone that is exposed at the crest of the mountains. The trail apex on the west side of the property is on the cuesta formed by Permian sandstone and limestone. The SMNHC buildings sit in the Triassic strike valley, and this overlook is on the Triassic cuesta along the SMNHC’s eastern boundary.
Stop 9: Triassic Cuesta
Late Triassic sandstone and conglomerate form a ridge here, also known as a cuesta. These 230-million-year-old rocks represent huge, Mississippi-size rivers that flowed from what is now Texas to a seashore near what is now the Utah-Nevada border.
Artist's representation of a Triassic amphibian