headward erosion
11waterfall — /waw teuhr fawl , wot euhr /, n. 1. a steep fall or flow of water in a watercourse from a height, as over a precipice; cascade. 2. a manner of arranging women s hair, as in long, loose waves. [bef. 1000; ME; OE waetergefeall. See WATER, FALL] * * …
12Bryce Canyon National Park — Infobox protected area | name = Bryce Canyon National Park iucn category = II caption = locator x = 60 locator y = 82 location = Garfield County and Kane County, Utah, USA nearest city = Tropic, Panguitch lat degrees = 37 lat minutes = 34 lat… …
13Rocky Mountains — the chief mountain system in North America, extending from central New Mexico to N Alaska. Highest peak, Mount McKinley, 20,300 ft. (6187 m). Also called Rockies. * * * or Rockies Mountain system, western North America. It extends some 3,000 mi… …
14Geography of Missouri — Physiographic map of Missouri (Legend) Courtesy USGS Missouri, a state near the geographical center of the United States, has three distinct physiographic divisions: * a north western upland plain or prairie region part of the Interior Plains… …
15Groundwater sapping — Scientists believe that groundwater sapping created these gullies in Noachis Terra on Mars. NASA image …
16gully — gully1 /gul ee/, n., pl. gullies, v., gullied, gullying. n. 1. a small valley or ravine originally worn away by running water and serving as a drainageway after prolonged heavy rains. 2. a ditch or gutter. 3. Cricket. a. the position of a fielder …
17Stream terrace — Stream terraces are relict features, such as floodplains, from periods when a stream was flowing at a higher elevation and has downcut to a lower elevation. Stream terraces often appear as plateaus on existing valley walls and indicate earlier… …
18Water gap — A water gap is an opening or notch which flowing water has carved through a mountain range. Water gaps often offer a practical route for roads and railroads to cross a mountain ridge. Geological implications A water gap is usually an indication… …
19Glaciology — (from Middle French dialect (Franco Provençal): glace , ice ; or Latin: glacies , frost, ice ; and Greek: λόγος, logos , speech lit. to talk about ice ) is the study of glaciers, or more generally ice and natural phenomena that involve ice.… …
20bog — bog1 boggish, adj. /bog, bawg/, n., v., bogged, bogging. n. 1. wet, spongy ground with soil composed mainly of decayed vegetable matter. 2. an area or stretch of such ground. v.t., v.i. 3. to sink in or as if in a bog (often fol. by down): We… …
