sheet erosion
81Great Lakes — a series of five lakes between the U.S. and Canada, comprising Lakes Erie, Huron, Michigan, Ontario, and Superior; connected with the Atlantic by the St. Lawrence River. * * * I Chain of lakes, central North America. Comprising Lakes Superior,… …
82Silurian Period — Interval of geologic time, 443–417 million years ago. The third period of the Paleozoic Era, the Silurian follows the Ordovician Period and precedes the Devonian. It marks the first appearance of land plants and jawed fishes. The continents were… …
83Water pollution — Raw sewage and industrial waste flows across international borders New River passes from Mexicali to Calexico, California. Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans and groundwater). Water p …
84Deep foundation — A deep foundation installation for a bridge in Napa, California, United States …
85Effects of global warming on Australia — This article is about predicted impacts of Climate change and Global warming on Australia and its climate. Australia is the highest emitter of greenhouse gases per capita in the developed world. [ [http://www.cana.net.au/index.php?site var=337… …
86climate change — Introduction periodic modification of Earth s climate brought about as a result of changes in the atmosphere as well as interactions between the atmosphere and various other geologic, chemical, biological, and geographic factors within the Earth …
87Dune — For other uses, see Dune (disambiguation). Erg Chebbi, Morocco …
88Missoula Floods — Glacial Lake Columbia (west) and Glacial Lake Missoula (east) are shown south of Cordilleran Ice Sheet. The areas inundated in the Columbia and Missoula floods are shown in red …
89Geology of the Grand Teton area — The geology of the Grand Teton area consists of some of the oldest rocks and one of the youngest mountain ranges in North America. The Teton Range, mostly located in Grand Teton National Park, started to grow some 9 million years ago. An older… …
90Beacon sandstone — The Beacon sandstone is a geological formation exposed in Antarctica and deposited from the Devonian to the Triassic ( Ma|400| Ma|225Verify source|date=April 2008). The sandstone was originally described as a formation, and upgraded to group and… …
