Speeton Beds
Encyclopedia
Speeton Beds, in English
geology
, a series of clay
s well exposed at Speeton
, near Filey
on the Yorkshire
coast.
Peculiar interest attaches to these beds for they are the principal representatives in Britain of the marine phase of the Lower Cretaceous system. The Speeton Clays pass downwards without break into the underlying Kimeridgian; they are capped by the Red chalk, which may be regarded as the equivalent of the Upper Gault of southern England. These beds thus form a passage series between marine Jurassic strata and those belonging undoubtedly to the Cretaceous system; in this way they correspond with the Purbeck-Wealden rocks, which form a connecting link between estuarine Jurassic
and Cretaceous strata.
Above the dark, bituminous, nodular shales with Kinseridge fossils at the base of the Speeton Clay comes the zone of Belemnites lateralis (35 feet), with Olcostephanus gravesiformis, O. rotula, and species of Hoplites and Oxynoticeras; this is followed by the zone of Betemnites jaculum, with B. crislatus, Olcostephanus (Astieria) ashen, O. (Simbirskites) inversus and O. (S.) Speetonensis in ascending order; Echinospatagus cordiformis, a species found in the typical Neocomian
area, also occurs in this zone. The next higher zone is that of Belemnites brunsvicensis (semicanaliculatus) (100 feet), with B. Speetonensis, Hoplites deshayesii, and Amaltheus bicurvatus. The topmost zone is characterized by Bet emnites nzinimus with Inoceramus concentricus and I. sulcatus; it consists of a few feet of mottled clays.
It appears, therefore, that while the lower portions of the Speeton Clay are the equivalents of the Wealden and perhaps of the Purbeck beds, the higher portions are the equivalents of the Lower Greensand and part of the Gault. In Lincolnshire the upper Speeton beds are represented by the Carstone and Tealby Limestone and Clay, and the lower Speeton by the Claxby Ironstone, Spilsby Sandstone and lower part of the Tealby clay. A similar faunal horizon is recognized in Heligoland and Russia.
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...
geology
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...
, a series of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
s well exposed at Speeton
Speeton
Speeton is a village in the civil parish of Reighton, in North Yorkshire, England. It lies near the edge of the coastal cliffs midway between Filey and Bridlington....
, near Filey
Filey
Filey is a small town and civil parish in North Yorkshire, England. It forms part of the borough of Scarborough and is located between Scarborough and Bridlington on the North Sea coast. Although it started out as a fishing village, it has a large beach and is a popular tourist resort...
on the 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...
coast.
Peculiar interest attaches to these beds for they are the principal representatives in Britain of the marine phase of the Lower Cretaceous system. The Speeton Clays pass downwards without break into the underlying Kimeridgian; they are capped by the Red chalk, which may be regarded as the equivalent of the Upper Gault of southern England. These beds thus form a passage series between marine Jurassic strata and those belonging undoubtedly to the Cretaceous system; in this way they correspond with the Purbeck-Wealden rocks, which form a connecting link between estuarine Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
and Cretaceous strata.
Above the dark, bituminous, nodular shales with Kinseridge fossils at the base of the Speeton Clay comes the zone of Belemnites lateralis (35 feet), with Olcostephanus gravesiformis, O. rotula, and species of Hoplites and Oxynoticeras; this is followed by the zone of Betemnites jaculum, with B. crislatus, Olcostephanus (Astieria) ashen, O. (Simbirskites) inversus and O. (S.) Speetonensis in ascending order; Echinospatagus cordiformis, a species found in the typical Neocomian
Neocomian
In geology, Neocomian was a name given to the lowest stage of the Cretaceous system. It was introduced by Jules Thurmann in 1835 on account of the development of these rocks at Neuchâtel , Switzerland. It has been employed in more than one sense. In the type area the rocks have been divided into...
area, also occurs in this zone. The next higher zone is that of Belemnites brunsvicensis (semicanaliculatus) (100 feet), with B. Speetonensis, Hoplites deshayesii, and Amaltheus bicurvatus. The topmost zone is characterized by Bet emnites nzinimus with Inoceramus concentricus and I. sulcatus; it consists of a few feet of mottled clays.
It appears, therefore, that while the lower portions of the Speeton Clay are the equivalents of the Wealden and perhaps of the Purbeck beds, the higher portions are the equivalents of the Lower Greensand and part of the Gault. In Lincolnshire the upper Speeton beds are represented by the Carstone and Tealby Limestone and Clay, and the lower Speeton by the Claxby Ironstone, Spilsby Sandstone and lower part of the Tealby clay. A similar faunal horizon is recognized in Heligoland and Russia.