Mount of the Holy Cross is located in the Colorado Rockies and was named for the thin white cross that appears on the side of the mountain as snow melts away in the summer.  Jackson photographed the mountain, and Thomas Moran painted it. 

Their work helped fuel an already budding fascination by the public in the symbolic significance of the mountain.  (See also: Moran's painting.)  In order to show the cross clearly, Jackson found that he had to climb a high ridge to get in just the right position and take his photographs in the morning when the sunlight cast just the right shadows.