Frost along the Firehole River. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell8824.html Bison moving in single file next to Firehole river, winter. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell49256.html Kepler Cascades of the Firehole River in winter. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell49340.html Midway Geyser Basin along the Firehole River. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell8810.html Thermal steam along the Firehole River in winter. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell49281.html Bison crossing Firehole River in winter. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell49271.html Firehole river and bison in winter. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell49258.html Snowy forest and Kepler Cascades. Yellowstone National Park, Wyoming, USA. http://www.terragalleria.com/parks/np-image.yell49339.html