page_title: Groundwater sapping
section_title: Mars
hierarchical_section_title: Groundwater sapping / Notable landmarks / Mars
caption_attribution_description: English: This image was cropped from an original that appears at: [1] The description of the original image reads as follows: Canyonlands National Park, Utah. Stillwater Canyon and Green River, looking southwest from Green River loop of river. Brown material covering nearby parts of the White Rim is the lower part of Overlook. Orange Cliffs in the background. Henry Mountains on the right skyline. Turks Head in the Moenkupi Formation. Figure 23, U.S. Geological Survey Bulletin 1327. Survey Bulletin-1327 Digital File:lsw00008 ID. Lohman, S.W. 8ct The original photo apparently was taken from Grand View Overlook in the park, probably in the early 1970s. A description of the publication in which the original was published in 1974 appears at [2]. The original was edited to focus on the smaller "theater-headed" canyons at left. The edited image was uploaded for use with the article entitled Groundwater sapping.
context_page_description: Groundwater sapping is a geomorphic erosion process that results in the headward migration of channels in response to near constant fluid discharge at a fixed point. The consistent flow of water displaces fine sediments which physically and chemically weathers rocks. Valleys that appear to have been created by groundwater sapping occur throughout the world in areas such as England, Colorado, Hawai’i, New Zealand, and many other places. However, it is difficult to characterize a landform as being formed exclusively by groundwater sapping due to phenomena such as pluvial runoff, plunge-pool undercutting, changes in water table level, and inconsistent groundwater flow. An example of drainage ways created purely by the outflow of subsurface fluids can be seen on the foreshores of beaches. As the surge of water and sand brought to land by a wave retreats seaward, the film of water becomes thinner until it forms rhomboid shaped patterns in the sand. Small fans form at the apex of the rhombic features, which are eventually fed by the remaining backflow of water traveling downslope.
context_section_description: Short, stream-like, deep channels have been observed on Mars. Very similar to valleys created by groundwater sapping here on Earth, the discovery of the Martian valleys has prompted numerous studies that aim to better understand the process of sapping.
caption: The two canyons at center-left in this photo from Canyonlands National Park in Utah have the theater-shaped heads typical of valley features shaped by groundwater sapping. The Green River is at right.
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