Images

A female mule deer, known as a doe, grazes near the entrance to the Caverns of Sonora.

A pool in the Caverns of Sonora. This cave, like many others, was formed by water combining with carbon dioxide to create a weak carbonic acid. This acid then dissolved the limestone to carve out chambers.

Helictite formations within the Caverns of Sonora. Helictite is a particular cave formation where a stalactite will grow at odd, curving angles due to pressure in the water.

A series of speleothems, or cave formations, in the Caverns of Sonora. Dripstone formations like stalactites (hanging from the ceiling) and stalagmites (growing from the floor) can be seen. In addition, bulbous speleothems known as "cave popcorn" grow on the walls.

An image of walls in the Caverns of Sonora. At the top of the image can be seen a form of flowstone known as draperies. At the base of the walls is a formation 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.

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.

Cave columns in the Caverns of Sonora. Columns form when stalactites and stalagmites fuse together. These columns then grew a series of bulbous formations known as "cave popcorn."

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

A detail image of "cave popcorn," a bulbous cave formation.

A cave wall showing several cave formations, or speleothems. The larger formations at the bottom formed submerged in water, whereas the smaller formations at the top were exposed to air when they formed.

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.

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.

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.

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.

Sheets of cave popcorn in the Caverns of Sonora.