The examples and perspective in this article deal primarily with the USA and other English-language countries and do not represent a worldwide view of the subject.(November 2015) |
A dissected plateau is a plateau area that has been severely eroded such that the relief is sharp. Such an area may be referred to as mountainous, but dissected plateaus are distinguishable from orogenic mountain belts by the lack of folding, metamorphism, extensive faulting, or magmatic activity that accompanies orogeny.
A dissected plateau may also be formed, or created, usually on a comparatively small scale, by the levelling of terrain by planing and deposition beneath an ice sheet or perhaps, an ice cap.[ citation needed ]
Subsequently, during the same or a later glacial, the margins of the glacial till plain are removed by glaciers, leaving the plateau into which erosion by water incises valleys. Such a plateau may be level or gently sloping but may be distinguished by the till caps on its hills. Glacial till is still widely known in Britain by the older name of boulder clay.[ citation needed ]
Dissected volcanic plateaus include the Pajarito Plateau in New Mexico, on the skirt of the enormous Valles Caldera. [1] Isolated portions of this plateau are known as mesas, and long, connected portions are known as potreros.
The Allegheny Plateau, [2] the Cumberland Plateau, [3] the Ozark Plateau, [4] and the Catskill Mountains [5] in the United States, the Blue Mountains and Hornsby Plateau in Australia and the Deccan Plateau in India are examples of dissected plateaus formed after regional uplift.[ citation needed ]
These older uplifts have been eroded by creeks and rivers to develop steep relief not immediately distinguishable from mountains.[ citation needed ]
Many areas of the Allegheny Plateau and the Cumberland Plateau, which are at the western edge of the Appalachian Mountains of eastern North America, are called "mountains" but are actually dissected plateaus. One can stand on the top of one of these high "mountains" and note that all the other tops are nearly the same height, which represents the original elevation profile of the plain before uplift, and thereafter the subsequent weather erosion.[ citation needed ]
Missouri, a state near the geographical center of the United States, has three distinct physiographic divisions:
In the context of physical geography, the Intermontane Plateaus is one of eight physiographic regions of the contiguous United States. The region consists mostly of plateaus and mountain ranges lying between the Rocky Mountains on the east and the Cascade and Sierra Nevada Mountains on the west. It is subdivided into three physiographic provinces: the Columbia Plateau in the north, the Basin and Range Province in the central and southwestern portions, and the Colorado Plateau in the southeast. In turn, each of these provinces are each subdivided into a number of physiographic sections.
The Ozarks, also known as the Ozark Mountains, Ozark Highlands or Ozark Plateau, is a physiographic region in the U.S. states of Missouri, Arkansas, Oklahoma and the extreme southeastern corner of Kansas. The Ozarks cover a significant portion of northern Arkansas and most of the southern half of Missouri, extending from Interstate 40 in central Arkansas to Interstate 70 in central Missouri.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of central North America, extending along the east flank of the Rocky Mountains from the Gulf Coast region to the Arctic Beaufort Sea. In Canada, it encompasses the Canadian Prairies separating the Canadian Rockies from the Canadian Shield, as well as the Boreal Plains and Taiga Plains east of the Mackenzie and Richardson Mountains; while in the United States, it includes the Great Plains of the West/Midwest and the tallgrass prairie region to the south of the Great Lakes extending east to the Appalachian Plateau region.
The Catskill Mountains, also known as the Catskills, are a physiographic province and subrange of the larger Appalachian Mountains, located in southeastern New York. As a cultural and geographic region, the Catskills are generally defined as those areas close to or within the borders of the Catskill Park, a 700,000-acre (2,800 km2) forest preserve protected from many forms of development under New York state law.
In geology and physical geography, a plateau, also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides have deep hills or escarpments. Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Plateaus are classified according to their surrounding environment as intermontane, piedmont, or continental. A few plateaus may have a small flat top while others have wider ones.
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 mountain ranges while the forces of erosion and weathering worked to tear them down. Even after many millions of years, records of Earth's great upheavals remain imprinted as textural variations and surface patterns that define distinctive landscapes or provinces.
The Cumberland Plateau is the southern part of the Appalachian Plateau in the Appalachian Mountains of the United States. It includes much of eastern Kentucky and Tennessee, and portions of northern Alabama and northwest Georgia. The terms "Allegheny Plateau" and the "Cumberland Plateau" both refer to the dissected plateau lands lying west of the main Appalachian Mountains. The terms stem from historical usage rather than geological difference, so there is no strict dividing line between the two. Two major rivers share the names of the plateaus, with the Allegheny River rising in the Allegheny Plateau and the Cumberland River rising in the Cumberland Plateau in Harlan County, Kentucky.
The Allegheny Plateau is a large dissected plateau area of the Appalachian Mountains in western and central New York, northern and western Pennsylvania, northern and western West Virginia, and eastern Ohio. It is divided into the unglaciated Allegheny Plateau and the glaciated Allegheny Plateau.
The Glaciated Allegheny Plateau is that portion of the Allegheny Plateau that lies within the area covered by the last glaciation. As a result, this area of the Allegheny Plateau has lower relief and gentler slopes than the relatively rugged Unglaciated Allegheny Plateau. In general, the glaciated lies to the north and west of the unglaciated, and forms an arc in northeastern to southeastern Ohio lying between the glacial till plains and the Unglaciated Allegheny Plateau. The Glaciated Allegheny Plateau extends into a belt of southern New York State and the central Susquehanna River basin.
The Allegheny Front is the major southeast- or east-facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, eastern West Virginia, and western Virginia. The Allegheny Front forms the boundary between the Ridge-and-Valley Appalachians to its east and the Appalachian Plateau to its west. The Front is closely associated with the Appalachian Mountains' Eastern Continental Divide, which in this area divides the waters of the Ohio/Mississippi river system, flowing to the Gulf of Mexico, from rivers flowing into Chesapeake Bay and from there into the Atlantic Ocean.
The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 1957.
The Endless Mountains are a geographical, geological, and cultural region in Northeastern Pennsylvania. The Endless Mountains region includes Bradford, Sullivan, Susquehanna,and Wyoming counties. The highest peak in the region is the North Knob of Elk Mountain at 2,693 feet. The dissected plateau is a subrange of the Appalachian Mountains.
The Driftless Area, also known as Bluff Country and the Paleozoic Plateau, is a topographical and cultural region in the Midwestern United States that comprises southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme northwestern corner of Illinois. The Driftless Area is a USDA Level III Ecoregion: Ecoregion 52. The Driftless Area takes up a large portion of the Upper Midwest forest–savanna transition. The Blufflands refers to the eastern section of the Driftless area in Minnesota, due to the steep bluffs and cliffs around the river valleys. The western half is known as the Rochester Plateau, which is flatter than the Blufflands. The Coulee Region refers to the southwestern part of the Driftless Area in Wisconsin. It is named for its numerous ravines.
Wills Mountain is a quartzite-capped ridge in the Ridge and Valley physiographic province of the Appalachian Mountains in Pennsylvania and Maryland, extending from near Bedford, Pennsylvania, to near Cumberland, Maryland. It is the northernmost of several mountain ridges included within the Wills Mountain Anticline.
The geology of Kansas encompasses the geologic history and the presently exposed rock and soil. Rock that crops out in the US state of Kansas was formed during the Phanerozoic eon, which consists of three geologic eras: the Paleozoic, Mesozoic and Cenozoic. Paleozoic rocks at the surface in Kansas are primarily from the Mississippian, Pennsylvanian, and Permian periods.
The Scandinavian Mountains or the Scandes is a mountain range that runs through the Scandinavian Peninsula. The western sides of the mountains drop precipitously into the North Sea and Norwegian Sea, forming the fjords of Norway, whereas to the northeast they gradually curve towards Finland. To the north they form the border between Norway and Sweden, reaching 2,000 metres (6,600 ft) high at the Arctic Circle. The mountain range just touches northwesternmost Finland but are scarcely more than hills at their northernmost extension at the North Cape.
The paleic surface or palaeic surface is an erosion surface of gentle slopes that exist in South Norway. Parts of it are a continuation of the Sub-Cambrian peneplain and Muddus Plains found further east or equivalent to the strandflat coastal plains of Norway. Hardangervidda, a particularly flat and elevated part of the Paleic surface formed in the Miocene at sea level.