420 STRATIGKAPHICAL GEOLOGY 



The Lincolnshire limestone frequently contains beds in which 

 corals are very abundant, and which have evidently been accu- 

 mulated in the neighbourhood of coral reefs. The upper layers, 

 too, invariably exhibit much current bedding, indicating shallow 

 water conditions. Ammonites are rare, but Echinoderms are 

 not uncommon. Gastropods (Natica, Nerincea, Patella, Pleuro- 

 tomaria, Trochus, Trochotoma] are common. Rhynchonellce and 

 Lamellibranchs of many species are abundant. The fauna has 

 eminently a shallow-water and coral-reef facies. This limestone 

 appears to represent the higher part of the Inferior Oolite of the 

 Cheltenham district from the Lower Trigonia Grit upward, for the 

 Ammonites quoted from it include Cceloceras Blagdeni, C. sub- 

 radiatum, Stepheoceras cf. Humphriesianum, and Oppelia Truelli, all 

 characteristic of the higher zones. Mr. Hudleston also considered 

 its Gastropod fauna to indicate the same part of the stage. 



In North Lincolnshire the limestone diminishes to about 60 

 feet, and in South Yorkshire the lower part is represented by shaly 

 limestones and the upper part by oolitic limestones, each set being 

 about 30 feet thick. 



Yorkshire. When they again emerge in North Yorkshire the 

 series has undergone much transformation, and the mass of the 

 Inferior Oolite consists of estuarine sandstones and shales. 14 Marine 

 beds, however, occur at the top and bottom, and also as a thin 

 zone in the midst of the Estuarine Series, the succession being as 

 follows, and the thicknesses those in the cliff sections : 



Feet. 

 5. Scarborough limestone . . . . 20 to 90 



4. Middle Estuarine Beds 50 to 100 



3. Millepore Beds (marine) 20 to 40 



2. Lower Estuarine Beds 200 to 280 



1. The " Dogger " sands and sandstone . . 30 to 36 



Average about 400 



1. Above the Liassic shales are yellow and grey micaceous sands 

 containing Grammoceras aalensis, Lingula Eeani, Rhynchonella 

 cynocephala. They are surmounted by a sandy oolitic ironstone, 

 which contains many fossils Ludwigia Murchisonce, Terebratula 

 trilineata, and Nerincea cingenda ; these sands and sandstone may 

 be regarded as the equivalent of the Northampton sands. 



2. The Lower Estuarine Series is exposed in the cliffs from 

 Kobin Hood's Bay to Huntcliff (see Fig. 140). The shales and 

 oolitic ironstones contain plant remains in some abundance. In the 

 midst of this series is a band of flaggy sandstone and ironstone with 

 marine fossils known as the Eller Beck Bed. It yields Gerrillia 

 acuta, Astarte minima, Pholadomya Heraulti, and other fossils. 



