Yoredale Series
Encyclopedia
The Yoredale Series, in geology
, is a local phase of the lower Carboniferous
rocks of the north of England
. The name was introduced by J. Phillips on account of the typical development of the phase in Yoredale (Wensleydale
), Yorkshire
.
rocks assume an aspect very different from that which obtains in the South. Beds of detrital sediment
, sandstone
s, shale
s and occasional ironstones and thin coal
s separate the limestone
s into well-defined beds. These limestone beds have received various names of local significance (Hardraw Scar, Simonstone
, Middle, Underset, Main and many others), and owing to the country being little disturbed by faulting
and being much cut up by the streams, they stand out as escarpments on either side of the valleys. The first indication of the intercalation of thick detrital deposits within the massive limestone is seen in Ingleborough
and Penyghent; but as the rocks are traced north the detrital matter increases in quantity and the limestones diminish, until in Northumberland
the whole Carboniferous series assumes the Yoredale phase, and consists of alternations of detrital and calcareous beds, no massive limestone being seen.
fauna usually associated with it. The main limestone of Weardale is full of coral
s, including Lonsdaleia floriformis, Dibunophyllum sp., Cyclophyllum pachyendothecum, etc., and has a typical Visean
fauna; it would therefore correspond, palaeontologically
, with the upper part of the Carboniferous Limestone of Derbyshire.
On Ingleborough the limestone is not very fossil
iferous, but the Main Limestone contains small corals of a zaphrentoid type and an upper Visean fauna. Posidonomya Becheri occurs fairly low down in the series in the Shale above the Hardraw Scar and Gayle limestones, but it is not accompanied by any of the goniatite
s or other cephalopod
s and lamellibranchs which characterize the Posidonomya Becheri beds of the Pendleside Series, the faunas of the Yoredale and Pendleside phases being very distinct.
The Red Bed Limestone of Leyburn, the uppermost limestone of the series, is very rich in fish remains, which are identical in many cases with those found in the topmost beds of the massive Carboniferous Limestone at Bolt Edge quarry in Derbyshire. The shales between the limestones are rich in fossils and contain abundant single corals referable to Zaphrentis enniskilleni, Cyclophyllum pachyendothecum, and others; these, though high-zonal forms, occur low down in the Yoredale strata, even in the shale above the Hardraw Scar limestone. In the Derbyshire area and farther north these corals would indicate the uppermost beds of the limestone series of those districts, and their early appearance in the Yoredale area is probably entirely due to conditions of environment.
Attempts have been made to correlate rocks in a number of widely separated areas with the Yoredale strata, but on wholly insufficient grounds. It is clear that the exact relationship which the Yoredale series of the type area bears as a whole to the lower Carboniferous rocks of the Midlands, north and south Wales
, etc., on the one hand, and to the Pendleside series on the other, has yet to be established on a firm palaeontological basis.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
, is a local phase of the lower Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
rocks of the north of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. The name was introduced by J. Phillips on account of the typical development of the phase in Yoredale (Wensleydale
Wensleydale
Wensleydale is the valley of the River Ure on the east side of the Pennines in North Yorkshire, England.Wensleydale lies in the Yorkshire Dales National Park – one of only a few valleys in the Dales not currently named after its principal river , but the older name, "Yoredale", can still be seen...
), Yorkshire
Yorkshire
Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform...
.
Properties and Condition
In the Yorkshire dales the CarboniferousCarboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
rocks assume an aspect very different from that which obtains in the South. Beds of detrital sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
, sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s, shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
s and occasional ironstones and thin coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
s separate the limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
s into well-defined beds. These limestone beds have received various names of local significance (Hardraw Scar, Simonstone
Simonstone, North Yorkshire
Simonstone is a hamlet near Hawes and Hardraw Force within the Yorkshire Dales in North Yorkshire, England....
, Middle, Underset, Main and many others), and owing to the country being little disturbed by faulting
Geologic fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...
and being much cut up by the streams, they stand out as escarpments on either side of the valleys. The first indication of the intercalation of thick detrital deposits within the massive limestone is seen in Ingleborough
Ingleborough
Ingleborough is the second highest mountain in the Yorkshire Dales. It is one of the Yorkshire Three Peaks, the other two being Whernside and Pen-y-ghent. Ingleborough is frequently climbed as part of the Yorkshire Three Peaks Challenge, which is a 24-mile circular challenge walk starting and...
and Penyghent; but as the rocks are traced north the detrital matter increases in quantity and the limestones diminish, until in Northumberland
Northumberland
Northumberland is the northernmost ceremonial county and a unitary district in North East England. For Eurostat purposes Northumberland is a NUTS 3 region and is one of three boroughs or unitary districts that comprise the "Northumberland and Tyne and Wear" NUTS 2 region...
the whole Carboniferous series assumes the Yoredale phase, and consists of alternations of detrital and calcareous beds, no massive limestone being seen.
Fossils
The Yoredale limestones are characterized by the presence of Productus giganteus and the brachiopodBrachiopod
Brachiopods are a phylum of marine animals that have hard "valves" on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection...
fauna usually associated with it. The main limestone of Weardale is full of coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s, including Lonsdaleia floriformis, Dibunophyllum sp., Cyclophyllum pachyendothecum, etc., and has a typical Visean
Viséan
The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from 345.3 ± 2.1 to 328.3 ± 1.6 Ma...
fauna; it would therefore correspond, palaeontologically
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
, with the upper part of the Carboniferous Limestone of Derbyshire.
On Ingleborough the limestone is not very fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
iferous, but the Main Limestone contains small corals of a zaphrentoid type and an upper Visean fauna. Posidonomya Becheri occurs fairly low down in the series in the Shale above the Hardraw Scar and Gayle limestones, but it is not accompanied by any of the goniatite
Goniatite
Goniatites are extinct ammonoids, shelled cephalopods related to squid, octopus, and belemnites, that form the order Goniatitida. The Gonatitida originated from within the more primitive anarcestine ammonoids in the Middle Devonian some 390 million years ago...
s or other cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s and lamellibranchs which characterize the Posidonomya Becheri beds of the Pendleside Series, the faunas of the Yoredale and Pendleside phases being very distinct.
The Red Bed Limestone of Leyburn, the uppermost limestone of the series, is very rich in fish remains, which are identical in many cases with those found in the topmost beds of the massive Carboniferous Limestone at Bolt Edge quarry in Derbyshire. The shales between the limestones are rich in fossils and contain abundant single corals referable to Zaphrentis enniskilleni, Cyclophyllum pachyendothecum, and others; these, though high-zonal forms, occur low down in the Yoredale strata, even in the shale above the Hardraw Scar limestone. In the Derbyshire area and farther north these corals would indicate the uppermost beds of the limestone series of those districts, and their early appearance in the Yoredale area is probably entirely due to conditions of environment.
Attempts have been made to correlate rocks in a number of widely separated areas with the Yoredale strata, but on wholly insufficient grounds. It is clear that the exact relationship which the Yoredale series of the type area bears as a whole to the lower Carboniferous rocks of the Midlands, north and south Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, etc., on the one hand, and to the Pendleside series on the other, has yet to be established on a firm palaeontological basis.