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Leitrim Group
The Leitrim Group is a lithostratigraphical term coined to refer to the succession of rock strata which occur in Northern Ireland within the Visean and Namurian stages of the Carboniferous Period. The group disconformably overlies the Dartry Limestone of the Tyrone Group. Stratigraphy The group comprises a series of shales and sandstones which in stratigraphic order (youngest/uppermost at top) are: Lackagh Sandstone Formation The formation is 60-90m thick in the Connaught Coalfield but only about 36m thick on Cuilcagh Mountain where it forms the prominent cliff-edged summit surface as also at Belmore.''Marble Arch Caves Global Geopark; Exploring the landscape of Fermanagh and Cavan'' (map), 2015 GSNI It is unfossiliferous. Gowlaun Shale Formation Some 50-60m thickness of shales and mudstones of Arnsbergian age constitute this formation. Briscloonagh Sandstone Formation About 53m of Pendleian age sandstones with interlayered siltstones and some mudstone make up this format ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group (stratigraphy)
In geology, a group is a lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into supergroups. Groups are useful for showing relationships between formations, and they are also useful for small-scale mapping or for studying the stratigraphy of large regions. Geologists exploring a new area have sometimes defined groups when they believe the strata within the groups can be divided into formations during subsequent investigations of the area. It is possible for only some of the strata making up a group to be divided into formations. An example of a group is the Glen Canyon Group, which includes (in ascending order) the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. Each of the formations can be distinguished from its neighbor by its lithology, but all were deposited in the same vast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
County Fermanagh
County Fermanagh ( ; ) is one of the thirty-two counties of Ireland, one of the nine counties of Ulster and one of the six counties of Northern Ireland. The county covers an area of 1,691 km2 (653 sq mi) and has a population of 61,805 as of 2011. Enniskillen is the county town and largest in both size and population. Fermanagh is one of four counties of Northern Ireland to have a majority of its population from a Catholic background, according to the 2011 census. Geography Fermanagh is situated in the southwest corner of Northern Ireland. It spans an area of 1,851 km2 (715 sq; mi), accounting for 13.2% of the landmass of Northern Ireland. Nearly a third of the county is covered by lakes and waterways, including Upper and Lower Lough Erne and the River Erne. Forests cover 14% of the landmass (42,000 hectares). It is the only county in Northern Ireland that does not border Lough Neagh. The county has three prominent upland areas: * the expansive We ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Ireland
The geology of Ireland consists of the study of the rock formations on the island of Ireland. It includes rocks from every age from Proterozoic to Holocene and a large variety of different rock types is represented. The basalt columns of the Giant's Causeway together with geologically significant sections of the adjacent coast have been declared a World Heritage Site. The geological detail follows the major events in Ireland's past based on the geological timescale. Timeline The oldest known Irish rock is about 1.7 billion years old and is found on Inishtrahull Island off the north coast of Ulster. Outcrops at Annagh Head on the Mullet Peninsula are almost as old. In other parts of Donegal, scientists have discovered rocks that originated as glacial deposits, demonstrating that at this early period, part of what was to become Ireland was in the grip of an ice age. However, because of the effects of later upheavals, it is almost impossible to sequence these early rock layers corre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous System Of Europe
The Carboniferous ( ) is a Period (geology), geologic period and System (stratigraphy), system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Myr, Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous'' means "coal-bearing", from the Latin ''wikt:carbo#Latin, carbō'' ("coal") and ''wikt:fero#Latin, ferō'' ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern 'system' names, it was coined by geologists William Conybeare (geologist), William Conybeare and William Phillips (geologist), William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian (geology), Mississippian and the later Pennsylvanian (geology), Pennsylvanian. Terrestrial animal life was well established by the Carboniferous Period. Stegocephalia, Tetrapods ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic Unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuilcagh Mountain
Cuilcagh () is a mountain on the border between County Fermanagh (in Northern Ireland) and County Cavan (in the Republic of Ireland). With a height of it is the highest point in both counties. It is also the 170th highest peak on the island of Ireland, and Ireland's only cross-border county top. Water from the southern slope flows underground until it emerges some miles away in the Shannon Pot, the traditional source of the River Shannon. The area is sometimes referred to as the Cuilcagh Mountains. Naming The name Cuilcagh comes from the Irish ''Cuilceach'', which has been translated as "chalky". However, the mountain is mainly sandstone and shale, covered with bog and heather. The cliff-edged summit surface of the mountain is formed from the hard-wearing Lackagh Sandstone which itself overlies the Briscloonagh Sandstone. "It is possible that the name refers to the limestone rock on the lower northern flanks, namely the Glencar and Dartry Limestone formations. Here a number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connaught Coalfield
Connacht ( ; ga, Connachta or ), is one of the provinces of Ireland, in the west of Ireland. Until the ninth century it consisted of several independent major Gaelic kingdoms (Uí Fiachrach, Uí Briúin, Uí Maine, Conmhaícne, and Delbhna). Between the reigns of Conchobar mac Taidg Mór (died 882) and his descendant, Aedh mac Ruaidri Ó Conchobair (reigned 1228–33), it became a kingdom under the rule of the Uí Briúin Aí dynasty, whose ruling sept adopted the surname Ua Conchobair. At its greatest extent, it incorporated the often independent Kingdom of Breifne, as well as vassalage from the lordships of western Mide and west Leinster. Two of its greatest kings, Tairrdelbach Ua Conchobair (1088–1156) and his son Ruaidri Ua Conchobair (c. 1115–1198) greatly expanded the kingdom's dominance, so much so that both became High King of Ireland. The Kingdom of Connacht collapsed in the 1230s because of civil war within the royal dynasty, which enabled widespread Hiberno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Period (geology)
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardized international units of geologic time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely define ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stage (stratigraphy)
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries. Rock series are divided into stages, just as geological epochs are divided into ages. Stages can be divided into smaller stratigraphic units called chronozones. (See chart at right for full terminology hierarchy.) Stages may also be divided into substages or indeed grouped as superstages. The term faunal stage is sometimes used, referring to the fact that the same fauna (animals) are found throughout the layer (by definition). Definition Stages are primarily defined by a consistent set of fossils (biostratigraphy) or a consistent magnetic polarity (see paleomagnetism) in the rock. Usually one or more index fossils that are common, found worldwide, easily recognized, and limited to a sing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Namurian
The Namurian is a stage in the regional stratigraphy of northwest Europe with an age between roughly 326 and 313 Ma (million years ago). It is a subdivision of the Carboniferous system or period and the regional Silesian series. The Namurian is named for the Belgian city and province of Namur where strata of this age occur (part of the Belgian Coal Measures). The Millstone Grit Group in the lithostratigraphy of northern England and parts of Wales is also of Namurian age. The Namurian age lasted from 326 to 313 million years ago. It is preceded by the Visean stage/age (which corresponds to the upper Carboniferous Limestone of Great Britain) and succeeded by the Westphalian stage/age (which corresponds to the lower and middle Coal Measures of Great Britain). In the official geologic timescale of the International Commission on Stratigraphy (ICS), the Namurian straddles the boundary between the Mississippian epoch (359-318 Ma) and the Pennsylvanian epoch (318-299 Ma). The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
