The rock wall display at the southwest entrance to Calvin Hall shows a cross-section of the eleven rock formations that occur between the center of the Zuni Mountains just southeast of Bluewater, and the Gallup area, with large representative samples of each rock type. The paint colors on the wall give an idea of how the different rock units are arranged underground. The oldest rock displayed is the Zuni Mountains Granite, which is approximately 1.4 billion years old. The youngest is the Crevasse Canyon Formation sandstone, about 86 million years old, which was deposited during the time dinosaurs lived in what is now New Mexico. This formation underlies the UNM-Gallup campus, and contains many leaf fossils of plants that are now extinct. The rocks in between are younger than the granite, but older than the Crevasse Canyon, and formed predominantly from sediments deposited by rivers and sand dunes. The Zuni Mountains formed when compressional forces about 70-50 million years ago pushed up a large, elongated dome of rock, with the ancient granite at its core, tilting the overlying, younger sedimentary rock layers, as shown on the wall. This event created the hogback that marks the western side of the Zuni Mountains and runs through the eastern part of Gallup.
Dr. Paula Watt, Chair / Arts and Sciences Division