SPEETON BEDS

This article appears in Volume V25, Page 633 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: SOU-STE

SPEETON BEDS , in English geology, a

series

SERIES (a Latin word from serere, to join)

of clays well exposed at Speeton, near Filey on the Yorkshire

coast

COAST (from Lat. costa, a rib, side)

. Peculiar

interest

INTEREST

attaches to these beds for they are the

principal

PRINCIPAL

representatives in Britain of the marine phase of the Lower Cretaceous

system

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

SERIES (a Latin word from serere, to join)

between marine Jurassic strata and those belonging undoubtedly to the Cretaceous

system

SYSTEM

; in this way they correspond with the Purbeck-

Wealden

WEALDEN

rocks, which form a connecting link between estuarine Jurassic and Cretaceous strata.
Above the dark, bituminous, nodular shales with Kimeridge fossils at the base of the Speeton Clay comes the zone of Belemnites lateralis (34 ft.), with Olcostephanus gravesiformis, 0. rotula, and species of Hoplites and Oxynoticeras; this is followed by the zone of Belemnites jaculum, with B. cristatus, Olcostephanus (Astieria) astieri, O. (Simbirskites) inversus and 0. (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) (loo ft.), with B. Speetonensis, Hoplites deshayesii, and Amaltheus bicurvatus. The topmost zone is characterized by Belemnites minima 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

WEALDEN

and perhaps of the Purbeck beds, the higher portions are the equivalents of the Lower

Greensand

GREENSAND

and part of the Gault. In Lincolnshire the upper Speeton beds are represented by the Carstone and Tealby Lime-stone and Clay, and the lower Speeton by the Claxby Ironstone, Spilsby

Sandstone

SANDSTONE

and lower part of the Tealby clay. A similar faunal horizon is recognized in Heligoland and

Russia

RUSSIA
RUSSIA (Rossiya)

.
See CRETACEOUS; NEOCOMIAN; KIMERIDGIAN; also G. W. Lamplugh, Q.J.G.S. (1889), xlv. (1896), Hi.; Rep. Brit. Assoc. (189o); A. Pavlow and G. W. Lamplugh,

Bull

. soc. imp. nat. Moscow (1891), and Q.J.G.S, (1897), liii.

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