There are 24 named waterfalls in Ricketts Glen State Park along Kitchen Creek as it flows in three steep, narrow valleys, or glens, in the U.S. state of Pennsylvania. They range in height from 9 feet (2.7 m) to the 94-foot (29 m) Ganoga Falls (see video). The park is named for R. Bruce Ricketts, a colonel in the American Civil War who owned over 80,000 acres (32,000 ha) in the area in the late 19th and early 20th centuries and spared the old growth forests in the glens from clearcutting. The park, which opened in 1944, is administered by the state's Bureau of State Parks. Nearly all of the waterfalls are visible from the Falls Trail built by Ricketts, which the state park rebuilt in the 1940s and late 1990s. The trail has been called "the most magnificent hike in the state" and one of "the top hikes in the East". The waterfalls are on the section of Kitchen Creek that flows down the Allegheny Front, a steep escarpment between the Allegheny Plateau to the north and the Ridge-and-Valley Appalachians to the south. The waterfalls are the result of increased flow in Kitchen Creek from glaciers enlarging its drainage basin during the last Ice Age. (Full article...)
The timeline of the Manhattan Project covers the research and development project that produced the first atomic bombs during World War II. The Manhattan Project was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major GeneralLeslie Groves of the US Army Corps of Engineers. The Army component of the project was designated the Manhattan District; "Manhattan" gradually became the codename for the entire project. Along the way, the project absorbed its earlier British counterpart, Tube Alloys. Two types of atomic bomb were developed during the war. A relatively simple gun-type fission weapon was made using uranium-235, an isotope that makes up only 0.7 percent of natural uranium. Since it is chemically identical to the most common isotope, uranium-238, and has almost the same mass, it proved difficult to separate. In parallel with the work on uranium was an effort to produce plutonium. The gun-type design proved impractical to use with plutonium so a more complex implosion-type nuclear weapon was developed in a concerted design and construction effort at the project's principal research and design laboratory in Los Alamos, New Mexico. (Full list...)
Deke Slayton (center) shows the adapter improvised by Ed Smylie so that carbon dioxide accumulating in Apollo 13's Lunar Module (LM) cabin could be removed using the Command Module's (CM) differently shaped lithium hydroxide canisters. After the spacecraft's oxygen tank exploded on April 13, 1970, the crew – Jim Lovell, Jack Swigert, and Fred Haise – faced severely limited power, a loss of cabin heat, a shortage of potable water, and a critical excess of carbon dioxide. They spent four days in the "two-person" LM, then returned to the CM and splashed down safely in the Pacific Ocean.
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