The Carboniferous is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 Ma to the beginning of the Permian Period, 298.9 Ma. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian.
The Llano Uplift is a geologically ancient, low geologic dome that is about 90 miles (140 km) in diameter and located mostly in Llano, Mason, San Saba, Gillespie, and Blanco counties, Texas. It consists of an island-like exposure of Precambrian igneous and metamorphic rocks surrounded by outcrops of Paleozoic and Cretaceous sedimentary strata. At their widest, the exposed Precambrian rocks extend about 65 miles (105 km) westward from the valley of the Colorado River and beneath a broad, gentle topographic basin drained by the Llano River. The subdued topographic basin is underlain by Precambrian rocks and bordered by a discontinuous rim of flat-topped hills. These hills are the dissected edge of the Edwards Plateau, which consist of overlying Cretaceous sedimentary strata. Within this basin and along its margin are down-faulted blocks and erosional remnants of Paleozoic strata which form prominent hills.
A polystrate fossil is a fossil of a single organism that extends through more than one geological stratum. The word polystrate is not a standard geological term. This term is typically found in creationist publications.
Sequence stratigraphy is a branch of geology, specifically a branch of stratigraphy, that attempts to discern and understand historic geology through time by subdividing and linking sedimentary deposits into unconformity bounded units on a variety of scales. The essence of the method is mapping of strata based on identification of surfaces which are assumed to represent time lines, thereby placing stratigraphy in chronostratigraphic framework allowing understanding of the evolution of the Earth's surface in a particular region through time. Sequence stratigraphy is a useful alternative to a purely lithostratigraphic approach, which emphasizes solely based on the compositional similarity of the lithology of rock units rather than time significance. Unconformities are particularly important in understanding geologic history because they represent erosional surfaces where there is a clear gap in the record. Conversely within a sequence the geologic record should be relatively continuous and complete record that is genetically related.
The Absaroka sequence was a cratonic sequence that extended from the end of the Mississippian through the Permian periods. There is an unconformity between the Absaroka and the lower Kaskaskia sequence. This unconformity divides the Carboniferous into the Mississippian and Pennsylvanian periods in North America.
The San Juan Basin is a geologic structural basin located near the Four Corners region of the Southwestern United States. The basin covers 7,500 square miles and resides in northwestern New Mexico, southwestern Colorado, and parts of Utah and Arizona. Specifically, the basin occupies space in the San Juan, Rio Arriba, Sandoval, and McKinley counties in New Mexico, and La Plata and Archuleta counties in Colorado. The basin extends roughly 100 miles (160 km) N-S and 90 miles (140 km) E-W.
Stratigraphic cycles refer to the transgressive and regressive sequences bounded by unconformities in the stratigraphic record on the cratons. These cycles represent a large scale eustasy cycle since the Cambrian period with further sub-divisions of those units.
A rhythmite consists of layers of sediment or sedimentary rock which are laid down with an obvious periodicity and regularity. They may be created by annual processes such as seasonally varying deposits reflecting variations in the runoff cycle, by shorter term processes such as tides, or by longer term processes such as periodic floods.
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Interior Seaway. The usage of the name Dakota for this particular Albian-Cenomanian strata is exceptionally widespread; from British Columbia and Alberta to Montana and Wisconsin to Colorado and Kansas to Utah and Arizona. It is famous for producing massive colorful rock formations in the Rocky Mountains and the Great Plains of the United States, and for preserving both dinosaur footprints and early deciduous tree leaves.
The Pennsylvanian Pottsville Formation is a mapped bedrock unit in Pennsylvania, western Maryland, West Virginia, Ohio, and Alabama. It is a major ridge-former in the Ridge-and-Valley Appalachians of the eastern United States. The Pottsville Formation is conspicuous at many sites along the Allegheny Front, the eastern escarpment of the Allegheny or Appalachian Plateau.
The Gulf of Suez Rift is a continental rift zone that was active between the Late Oligocene and the end of the Miocene. It represented a continuation of the Red Sea Rift until break-up occurred in the middle Miocene, with most of the displacement on the newly developed Red Sea spreading centre being accommodated by the Dead Sea Transform. During its brief post-rift history, the deepest part of the remnant rift topography has been filled by the sea, creating the Gulf of Suez.
The sea-level curve is the representation of the changes of the sea level relative to present day mean sea level as gleaned from the stratigraphic record throughout the geological history.
In lithostratigraphy, coal measures are coal-bearing strata, with the term typically applied to European units of the Upper Carboniferous System.
The Glenshaw Formation is a mapped sedimentary bedrock unit in Pennsylvania, Maryland, West Virginia, and Ohio, of Pennsylvanian age. It is the lower of two formations in the Conemaugh Group, the upper being the Casselman Formation. The boundary between these two units is the top of the marine Ames Limestone. The Conemaugh Group overlies the Upper Freeport coal bed of the Allegheny Formation and underlies the Pittsburgh coal seam of the Monongahela Group.
The Lower Permian Esplanade Sandstone is a cliff-forming, resistant sandstone, dark red, geologic unit found in the Grand Canyon. The rock unit forms a resistant shelf in the west Grand Canyon, south side of the Colorado River, at the east of the Toroweap Fault, down-dropped to west, southeast of Toroweap Overlook, and west of Havasupai. The red, sandstone shelf, The Esplanade is about 20-mi long. At Toroweap Overlook region, Toroweap Valley with Vulcan's Throne, Uinkaret volcanic field, the resistant Esplanade Sandstone is described in access routes exploring the Toroweap Lake area.
The Supai Group is a slope-forming section of red bed deposits found in the Colorado Plateau. The group was laid down during the Pennsylvanian to Lower Permian. Cliff-forming interbeds of sandstone are noticeable throughout the group. The Supai Group is especially exposed throughout the Grand Canyon in northwest Arizona, as well as local regions of southwest Utah, such as the Virgin River valley region. It occurs in Arizona at Chino Point, Sycamore Canyon, and famously at Sedona as parts of Oak Creek Canyon. In the Sedona region, it is overlain by the Hermit Formation, and the colorful Schnebly Hill Formation.
The Bluefield Formation is a geologic formation in West Virginia. It preserves fossils dating back to the Mississippian subperiod of the Carboniferous period. Sediments of this age formed along a large marine basin lying in the region of what is now the Appalachian Plateau. The Bluefield Formation is the lowest section of the primarily siliciclastic Mauch Chunk Group, underlying the Stony Gap Sandstone Member of the Hinton Formation and overlying the limestone-rich Greenbrier Group.
The Washington Formation is a coal, sandstone, and limestone geologic formation located in Ohio, Pennsylvania and West Virginia. It dates back to the Lower Permian period, with its base at or near the Permian/Carboniferous boundary. The Washington formation and the Dunkard Group as a whole was deposited at a time when the continents were in the process of forming the "Super Continent" Pangaea as well as a gradual drop in sea levels. The result during this period was coals being thinner and impure with high ash content. The limestones found with in the formation are exclusively freshwater deposits.
One of the major depositional strata in the Himalaya is the Lesser Himalayan Strata from the Paleozoic to Mesozoic eras. It had a quite different marine succession during the Paleozoic, as most parts of it are sparsely fossiliferous or even devoid of any well-defined fossils. Moreover, it consists of many varied lithofacies, making correlation work more difficult. This article describes the major formations of the Paleozoic – Mesozoic Lesser Himalayan Strata, including the Tal Formation, Gondwana Strata, Singtali Formation and Subathu Formation.
The Arkoma Basin is a peripheral foreland basin that extends from central west Arkansas to south eastern Oklahoma. The basin lies in between the Ozark Uplift and Oklahoma Platform to the north and Ouachita Mountains to the south and with an area of approximately 33,800 mi2. Along the southern edge of the basin, the Choctaw Fault is the boundary that separates the mountains from the basin itself. This basin is one of seven that lie along the front of the Ouachita and Appalachian mountain systems. This basin is Oklahoma's fourth largest in terms of natural gas production. Oil has been extracted locally, but not on a commercial scale. Coal was the first natural resource used commercially within the basin. Surface mapping of coal seams in the early part of the 20th century lead to the discovery of sub-surface features that indicated the presence of natural gas. Mansfield, Arkansas was the site of the first natural gas discovery in 1902.
