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Great Falls Of The Potomac River
Great Falls is a series of rapids and waterfalls on the Potomac River, upstream from Washington, D.C., on the border of Montgomery County, Maryland and Fairfax County, Virginia. The Potomac and the falls themselves are legally entirely within Maryland, since the state's border follows the south bank of the river. Great Falls Park, managed as part of George Washington Memorial Parkway, is on the southern banks in Virginia, and Chesapeake and Ohio Canal National Historical Park parkland is along the northern banks of the river in Maryland. Both are operated by the National Park Service. The Great Falls area is popular for outdoor activities such as kayaking, whitewater rafting, rock climbing, and hiking. The Billy Goat Trail on Bear Island, and Olmsted Island, both accessible from Maryland, offer scenic views of the Great Falls. There also are overlook points on the Virginia side. Great Falls and Little Falls (about 5 miles downstream) are named in contradistinction to one an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Virginia
Northern Virginia, locally referred to as NOVA or NoVA, comprises several County (United States), counties and independent city (United States), independent cities in the Commonwealth (U.S. state), Commonwealth of Virginia in the United States. The region radiates westward and southward from Washington, D.C., the nation's capital, and has a population of 3,257,133 people as of 2023 United States Census Bureau, U.S. Census Bureau estimates, representing over a third of the state's total population. It is the most populous region in both Virginia and the regional Washington metropolitan area. Communities in the region form the Virginia portion of the Washington metropolitan area and the larger Washington–Baltimore combined statistical area, Washington–Baltimore metropolitan area. Northern Virginia has a significantly larger job base than either Washington, D.C. or the Maryland portion of its suburbs, and is the highest-income region of Virginia, with several of the List of high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olmsted Island
Olmsted Island is a small island in the middle of the Potomac River in the U.S. state of Maryland, near Great Falls of the Potomac River, Great Falls which is a part of C & O Canal National Historical Park, located across the river from Great Falls Park. It is a part of Potomac, Maryland. Named for Frederick Law Olmsted Jr., the landscape architect and preservationist whose famous father designed New York's Central Park, the small island is a bedrock terrace forest that supports rare, threatened and endangered plant species. The island is very rocky and has steep cliffs that face the river, where it has been eroded over time. It also has trees and vegetation. One might also spy a heron, small lizard or wild goose here. The total area of the island (estimating from calibrated satellite footage) is no more than 0.2 square kilometers. A fenced-in wooden tourist walkway winds along the southern part of the island. For the purpose of protecting the island's natural wildlife, v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chesapeake And Ohio Canal
The Chesapeake and Ohio Canal, abbreviated as the C&O Canal and occasionally called the Grand Old Ditch, operated from 1831 until 1924 along the Potomac River between Washington, D.C., and Cumberland, Maryland. It replaced the Patowmack Canal, which shut down completely in 1828, and could operate during months in which the water level was too low for the former canal. The canal's principal cargo was coal from the Allegheny Mountains. Construction began in 1828 on the canal and ended in 1850 with the completion of a stretch to Cumberland, although the Baltimore and Ohio Railroad had already reached Cumberland in 1842. The canal had an elevation change of which required 74 canal locks, 11 aqueducts to cross major streams, more than 240 culverts to cross smaller streams, and the Paw Paw Tunnel. A planned section to the Ohio River in Pittsburgh was never built. The canal is now maintained as the Chesapeake and Ohio Canal National Historical Park, with a trail that follows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Washington
George Washington (, 1799) was a Founding Fathers of the United States, Founding Father and the first president of the United States, serving from 1789 to 1797. As commander of the Continental Army, Washington led Patriot (American Revolution), Patriot forces to victory in the American Revolutionary War against the British Empire. He is commonly known as the Father of the Nation for his role in bringing about American independence. Born in the Colony of Virginia, Washington became the commander of the Virginia Regiment during the French and Indian War (1754–1763). He was later elected to the Virginia House of Burgesses, and opposed the perceived oppression of the American colonists by the British Crown. When the American Revolutionary War against the British began in 1775, Washington was appointed Commanding General of the United States Army, commander-in-chief of the Continental Army. He directed a poorly organized and equipped force against disciplined British troops. Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patowmack Canal
The Patowmack Canal, sometimes called the Potomac Canal, is a series of five inoperative canals located in Maryland and Virginia, United States, that was designed to bypass rapids in the Potomac River upstream of the present Washington, D.C., area. The most well known of them is the Great Falls skirting canal, whose remains are managed by the National Park Service since it is within Great Falls Park, an integral part of the George Washington Memorial Parkway. The first section of the canal opened in 1795, and the canal ended operations in 1828. History Planning the canal Few ventures were dearer to George Washington than his plan to make the Potomac River navigable as far as the Ohio River Valley. In the uncertain period after the Revolutionary War, Washington believed that better transportation and trade would draw lands west of the Allegheny Mountains into the United States and "bind those people to us by a chain which never can be broken." "The way," Washington wrote, " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downcutting
Downcutting, also called erosional downcutting, downward erosion or vertical erosion, is a geological process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream bed or the valley floor. The speed of downcutting depends on the stream's ''base level'', the lowest point to which the stream can erode. Sea level is the ultimate base level, but many streams have a higher "temporary" base level because they empty into another body of water that is above sea level or encounter bedrock that resists erosion. A concurrent process called '' lateral erosion'' is the widening of a stream channel or valley. When a stream is high above its base level, downcutting will take place faster than lateral erosion; but as the level of the stream approaches its base level, the rate of lateral erosion increases. This is why streams in mountainous areas tend to be narrow and swift, forming V-shaped valleys, while streams in lowland areas tend to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gneisses
Gneiss (pronounced ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures ranging from 2 to 15 kbar, sometimes even more, and temperatures over 300 °C (572 °F). Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct cleavage. Gneisses are common in the ancient crust of continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss. Description Orthogneiss from the Czech Republic In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding (gneissic banding) but poorly developed schistosity and indistinct cleavage. In other words, it is a metamorphic rock composed of mineral grains easily seen with the unaided eye, which f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schist
Schist ( ) is a medium-grained metamorphic rock generally derived from fine-grained sedimentary rock, like shale. It shows pronounced ''schistosity'' (named for the rock). This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes or plates. This texture (geology), texture reflects a high content of platy minerals, such as mica, talc, chlorite group, chlorite, or graphite. These are often interleaved with more granular minerals, such as feldspar or quartz. Schist typically forms during regional metamorphism accompanying the process of mountain building (orogeny) and usually reflects a medium Metamorphism#Metamorphic grades, grade of metamorphism. Schist can form from many different kinds of rocks, including sedimentary rocks such as mudstones and igneous rocks such as tuffs. Schist metamorphosed from mudstone is particularly common and is often very rich in mica (a ''mica schis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphic Rock
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causing profound physical or chemical changes. During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by their protolith, their chemical and mineral makeup, and their texture. They may be formed simply by being deeply buried beneath the Earth's surface, where they are subject to high temperatures and the great pressure of the rock layers above. They can also form from tectonic processes such as continental collisions, which cause horizontal pressure, friction, and dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precambrian
The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinized name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons ( Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago ( Ga) to the beginning of the Cambrian Period, about million years ago ( Ma), when hard-shelled creatures first appeared in abundance. Overview Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what is known has largely been discovered from the 1960s onwards. The Precambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1936 Northeastern United States Flood
The 1936 Northeastern United States flood was a historic flood that occurred across the Northeastern United States, as well as the Mid-Atlantic region and Ohio, in March 1936. Record-setting flooding after a combination of a particularly precipitation-heavy winter and large amounts of rainfall in March caused severe damage across the region. Record heights were recorded in many rivers, including the Connecticut River, which peaked at in Hartford, the Merrimack River, the Pemigewasset River, and the Androscoggin River. The flood led to an estimated 150 to 200 deaths across the Northeast, and hundreds of millions of dollars in damage in 1936 dollars. $100 million in 1936 dollars is equivalent in purchasing power to about $2.2 billion in 2023. Background The winter of 1935–36 was particularly cold, and more snowfall than usual fell in the Northeast. When March arrived, along with warmer temperatures, this snow began to melt, causing water levels in rivers to rise. This was a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
