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Geology of the United States. Shaded relief map of the United States, showing 10 geological provinces. The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Over the 4.5 billion-year history of the Earth, tectonic upheavals and colliding plates have raised great ...
The United States expropriated from Panama additional areas around the soon-to-be-built Madden Dam and annexed them to the Panama Canal Zone. [363] [371] Caribbean Sea: May 3, 1932 The United States adjusted the border at Punta Paitilla in the Canal Zone, returning a small amount of land to Panama. This was the site for a planned new American ...
The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards ...
The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [3] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...
The cartography of the United States is the history of surveying and creation of maps of the United States. Maps of the New World had been produced since the 16th century. The history of cartography of the United States begins in the 18th century, after the declared independence of the original Thirteen Colonies on July 4, 1776, during the ...
The state with the most national parks is California with nine, followed by Alaska with eight, Utah with five, and Colorado with four. The largest national park is Wrangell–St. Elias in Alaska: at over 8 million acres (32,375 km 2), it is larger than each of the nine smallest states.
The United States is a major exporter of agricultural products. The southern portion of the Great Plains lies over the Ogallala Aquifer , a huge underground layer of water-bearing strata. Center pivot irrigation is used extensively in drier sections of the Great Plains, resulting in aquifer depletion at a rate that is greater than the ground's ...
The United States Bicycle Route System (abbreviated USBRS) is the national cycling route network of the United States. It consists of interstate long-distance cycling routes that use multiple types of bicycling infrastructure, including off-road paths, bicycle lanes, and low-traffic roads. As with the complementary United States Numbered ...