Geology of the SMNHC
Tour Introduction
Join Dr. Spencer Lucas from the New Mexico Museum of Natural History and Science as he highlights geologic features along the trails at the Sandia Mountain Natural History. Gain an understanding of the geology and rocks unearthed here, and what they teach us about our part of the mountain.
Geology Resources
View and download accessible PDF files.
- SMNHC Geology Trail Brochure (PDF)
- Fossil Hunt Guide (PDF) Identify and learn about limestone fossils in the Sandias.
- SMNHC Geology Research Paper (PDF) A published journal article by Dr. Spencer Lucas, et al., entitled "The Permian-Triassic Stratigraphic Section at the Sandia Mountain Natural History Center
Take the Tour!
Stop 1: Fossil Area
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.

Close-up of a Bryozoan Fossil.

Learn more about animal fossils found by
downloading our Fossil Hunt Guide.
Stop 2: Glorieta-San Andres Contact
Stop 3: Oldest Bedrock
Stop 4: Shark's Tooth
Stop 4: Shark's Tooth

Shark tooth on limestone boulder. 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
Stop 6: Paradise Benches
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
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).

Moenkopi sandstone at the microscopic level
Stop 8: Overlook
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 dip slope 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.