Big Bend National Park

Cooling cracks in rhyolite. The weathered surface under Cain's feet is the exposed edge of an intrusive igneous feature, probably a dike or an uplifted sill.

Trail Marker 7

Mexican Drooping Juniper is a member of the Juniper family that is fairly common in Mexico but can only be found in the Chisos Mountains in the United States. Even though it appears to be on death's door, it's not. Wilted leaves are a year-round characteristic of the Drooping Juniper.

Biological erosion. Green lichen on rock. Lichen is a symbiotic relationship between two plants: a fungus on the top, and algae on the bottom. Lichen is a biological erosive agent, since the acids lichen produce chemically erode the rock surface. Over a long period of time, lichen turns rock into soil.

Trail Marker 12

Juniper Canyon is a fault block feature formed when massive regional faulting caused some blocks of land to rise and others to fall. The valley floor is a graben fault and the walls are horst faults. The fault planes are on either side of the valley. Other fault block features are visible in the distance.