Images

An image of the exit to the Caverns of Sonora. Unlike the rest of the cave, which had been weathered by water, this portion of the cave had been weathered by air moving through the limestone.

A vertical shaft within the cave that shows how faulting and fractures in the rock create openings for air and water to weather and ultimately create a cave.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the border of Texas and Mexico. This view is of the cliffs of Diablo East. Prickly pear cacti are common around the reservoir.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the border of Texas and Mexico.

The Caverns of Sonora have numerous types of speleothems, or cave formations. In this image, stalactites can be seen hanging from the ceiling and all along the walls are small formations known as "cave popcorn."

The Caverns of Sonora have numerous types of speleothems, or cave formations. In this image, stalactites can be seen hanging from the ceiling; stalagmites can be seen rising from the floor; and all along the walls are small formations known as "cave popcorn."

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others.

An image of the exit to the Caverns of Sonora. Unlike the rest of the cave, which had been weathered by water, this portion of the cave had been weathered by air moving through the limestone.

A series of speleothems, or cave formations, in the Caverns of Sonora.

A small chamber of speleothems, otherwise known as cave formations. The ones that descend vertically are known as stalactites, whereas the ones that extend horizontally or diagonally are known as helictites.

These sections of the Caverns of Sonora were carved by the wind, rather than by water. As such, they have smooth walls.

A prominent cave column in the Caverns of Sonora. Cave columns occur when stalactites and stalagmites fuse together. This column then grew a series of cave formations, or speleothems, known as "cave popcorn."

A unique speleothem, or cave, formation can be seen here: helictites. Helictites are undulating dripstone formations that, due to differential pressures in the water, grow in unusual directions. These helictites are in the Caverns of Sonora.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others. Prickly pear cacti are common along the banks of the reservoir.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the border of Texas and Mexico. This image shows the bridge portion of US 90 as it crosses the reservoir.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others.

Amistad National Recreation Area includes the Amistad Reservoir, a man-made lake along the Texas and Mexico border. It is fed by the Rio Grande, Devils River, and the Pecos River, among others.

A female mule deer, called a doe, forages near the Caverns of Sonora in Texas.

A series of speleothems, or cave formations, in the Caverns of Sonora. A prior waterline can be seen in the formations where the color changes from primarily white (formations formed in the air) to more beige (formations formed underwater). In addition, the previously submerged formations are larger than the ones that formed above the waterline.