Editing Natural arch (section)

==Weather-eroded arches==
[[File:Metate Arch, Devils Garden, Grand Staircase-Escalante National Monument, Utah, USA.jpg|left|thumb|Metate Arch, [[Devils Garden (Grand Staircase–Escalante National Monument)|Devils Garden (GSENM)]], a very thin arch near the end of its life]]
Weather-eroded arches begin their formation as deep cracks which penetrate into a sandstone layer. Erosion occurring within the cracks wears away exposed rock layers and enlarges the surface cracks isolating narrow sandstone walls which are called fins. Alternating frosts and thawing cause crumbling and flaking of the porous sandstone and eventually cut through some of the fins. The resulting holes become enlarged to arch proportions by rockfalls and weathering. The arches eventually collapse leaving only buttresses that in time will erode.<ref>{{cite web |url=http://www.nature.nps.gov/geology/parks/arch/ |title=Geology Resources, Arches National Park |publisher=National Park Service |access-date=December 23, 2015 |url-status=live |archive-url=https://web.archive.org/web/20151223190124/http://www.nature.nps.gov/geology/parks/arch/ |archive-date=December 23, 2015 }}</ref>

Many weather-eroded arches are found in [[Arches National Park]], [[Canyonlands National Park]], and [[Grand Staircase–Escalante National Monument]] (GSENM), all located in southern Utah, United States.
{{wide image|Hoodoo formation-Big.jpg|600px|Progressive erosion producing plateau, fin, window (or arch), and hoodoos}}