INTHOBTJCTION. 1 9 



consisting largely of rounded blocks (the so-called doggers) of 

 sandstone and ironstone. 



The Lower Estuwrine Series, exposed at various localities on the 

 coast between Eobin Hood Bay and Huntclifl (the latter is situated 

 a few miles further north than the coastline shown in the map), 

 consists of a considerable thickness of arenaceous and argillaceous 

 sediments, associated with beds of oolitic ironstone, thin coal-seams, 

 and an abundance of carbonaceous matter. This succession of 

 estuarine sediments containing plant remains is capped by a thin 

 marine band known as the Mler Beck led. This is succeeded by 

 the Millepore hed, so called from the occurrence of the Polyzoan 

 Maploxoia straminea ^ (Phill.) ( = Millepora and Cricopora straminsa), 

 which consists of ferruginous sandstone and limestone, and is 

 exposed at Cloughton Wyke in its arenaceous faoies, and at Gris- 

 thorpe Bay and Cayton Bay as a limestone. Above the Millepore 

 bed we pass up into the second series of freshwater or estuarine 

 beds, known as the Middle Estuarine Series. These deposits 

 constitute the principal coal-bearing series in the Inferior Oolite, 

 and include the famous plant -bed of Gristhorpe Bay. Prom the 

 Middle Estuarine rocks a certain amount of jet has been obtained ; 

 but most of the well-known Whitby jet is of Upper Liassic age. 



Another marine intercalation, the Scarborough or Grey Limestone 

 Series, rests on the Middle Estuarine beds ; these blue and grey 

 limestones, exposed in the cliffs at Cloughton "Wyke, form the most 

 important marine development in the Yorkshire Oolites. Besting 

 on the Scarborough limestones there is a third succession of fresh- 

 water strata, known as the Upper Estuarine Series, consisting of 

 hard siliceous rocks, sandstones, shales, and ironstones, including 

 much carbonaceous matter. Some species of plants have been 

 obtained from sandstone strata in the lower part of this third 

 Estuarine Series, which occupies nearly the whole of the moorlands 

 of the East Yorkshire area. 



At the summit of the Inferior Oolite we have the CornbrasTi, 

 so named by William Smith, which is made up of calcareous beds 

 containing abundant marinfe fossils, and is exposed in the Cayton 

 and Gristhorpe Bay sections. 



Gregory (96), p. 159. 



