This photo is a good example of the fins that form from erosion.
Arches National Park is in eastern Utah a few miles north of Moab. It is known for preserving over 2000 natural stone arches, including the world-famous Delicate Arch ( of which I don't have a photo because we did not hike in that part of the park) in addition to a variety of unique geological formations. The park lies above a sub-terranian salt bed, which is the main cause of the formation of the arches, spires, balanced rocks, and sandstone fins. Over time, water seeped into the surface cracks, joints, and folds of these layers. Ice formed in the fissures, expanding and putting pressure on surrounding rock, breaking off bits and pieces. Winds later cleaned out the loose particles. A series of free-standing fins remained. Wind and water attacked these fins until, in some, the cementing material gave way and chunks of rock tumbled out. Many damaged fins collapsed. Others, with the right degree of hardness and balance, survived despite their missing sections. These became the famous arches. (wiki is my source)
This area was part of Edward Abbey's home turf and he was actually a park ranger there for one year in the late 60's. Thus was born the novel Desert Solitaire, a must~read for any quasi~environmentalist. It has reached biblical proportion among more than a few. It is such a quotable read. Such as: Wilderness is not a luxury but a necessity of the human spirit, and as vital to our lives as water and good bread. A civilization which destroys what little remains of the wild, the spare, the original, is cutting itself off from its origins and betraying the principle of civilization itself."
We passed by about 6 or 7 arches on this hike. We even passed a huge arch that had recently collapsed.
We could literally spend an entire week here hiking all day, every day and still only cover a small portion of the park. We entered through the main entrance, since we have a national parks membership pass, but it is also possible to enter for free along a long, winding and sandy back road. Your vehicle needs pretty high clearance to make it but it would be well worth the trouble just to avoid the throngs of tourists that rarely venture much farther than the parking lots closest to whatever arch they want to photograph.