A photo of Mariscal Mine area.

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