The Big Bend of Texas is fascinating. Its unique combination of arid plains, stark mountains, steep canyons, and geological formations is found nowhere else on earth. The large circular feature in the middle top portion of the image is the Solitario, an 8 mile diameter volcanic dome called a laccolith. It was formed around 37 million years ago and is one of the best examples of its kind. Similar geological features can be seen south of the river. The Rio Grande River cuts across the middle of the image as it flows into Santa Elena Canyon at the right edge. Although the Rio Grande has contributed to the creation of this canyon, it initially was formed 100 million years ago by a shift in the Santa Elena fault well before the Rio Grande existed. An expanded view of this region is given by Bothsides.

The area covered by this image is approximately 35x46 miles. A full-resolution crop of the image file is available here that shows the detail present in the full image print.