| Spring thunderstorms bring rain to Chisos Mountains and the Chihuahuan Desert in Big Bend. This view is looking north from the Mariscal Mine area. Low buttes capped with remnants Tertiary-age volcanic flows are to the right. These lava flows rest on top of Late Cretaceous-age sedimentary rocks (Aguja Formation). The Chisos Mountains are the eroded remnant of massive igneous plutons and associated igneous rocks that formed in the Eocene and Oligocene time (Early Tertiary) (see Scheubl and Mruk, 1994 for a discussion on igneous rocks of the Chisos Mountains). |
