This is the spillway at Ft. Peck Dam, a large earthen dam near Ft. Peck, Montana.

This one is probably my favorite picture from the whole trip; the lighting and clouds were just incredible. Silhouetted in the foreground are the two hydroelectric powerhouses at Ft. Peck dam; they're cement-block buildings, each about 200 feet tall.

MacDonald Lake at Glacier National Park.

This is a geyser at Yellowstone; I neglected to write down which one it is, sorry. ;) I liked the effect of the sun shining through the steam and spray.

The Grand Canyon of the Yellowstone. The color didn't come out in the picture quite as well as I'd hoped, but I still think it's an impressive scene.