16 



UPPER LIAS. 



Terebratula globata. M. C. t. 436. f. 1. 



Trigonia costata. M. C. t. 85. 



striata, M. C. t. 237- f. 1 3 2 & 3. 



Unio ahductus. Phill. pi. 11. fig. 42. 



media. M. C. t. 83. f. 7. 

 obsoleta. M. C. t. 83. 

 perovalis. M. C . t. 43 6 . f . 2 & 3 . 



Should the observer extend his range to the south-west, he may trace similar strata, 

 containing many of the same species of fossils, from Gloucestershire through Somerset- 

 shire, to the coast cliffs at Bridport, Dorsetshire, where he will see the beds laid bare, 

 dipping under younger formations, and resting upon the Lias, as in the Cotteswold 

 Hills. In like manner, if he follow these beds north-eastward, he will find their re- 

 presentatives occupying similar positions in the Oolitic escarpment of the counties of 

 Oxford, Northampton, Rutland, and Lincolnshire, and thence extending to the high 

 and rugged cliffs between Scarborough and Whitby in Yorkshire 1 , 



The Lias, or base of the Oolitic System, forms the subsoil of the whole of the Vale of 

 Gloucester, extending from the Cotteswold Hills to the Severn. Like the Inferior 

 Oolite, this formation may be followed on the south-west to Lyme Regis 2 in Dor- 

 setshire, and on the north-east to Whitby in Yorkshire. Near the latter place it is 

 more fully developed than in any other part of the kingdom, and has there been divided 

 by Professor Phillips into three parts. A fourfold division, however, is practicable in 

 Gloucestershire and Worcestershire, viz. 



The Upper Lias Shale (d. of section, p. 11.) consists of a bluish clay, containing occa- 

 sionally nodules, or spherical concretions of dark argillaceous limestone, called in York- 

 shire and elsewhere "cement stones." This subgroup ranges along the escarpment of 

 the Cotteswold Hills, and may be seen on the sides of many of the roads where they 

 begin to descend from the hills into the valley of the Severn. In this stratum I have 

 observed the following organic remains. 



1 See the Geological Map of England and Wales, by Mr. Greenough. Those who desire to obtain a full 

 knowledge of the different localities in which the same species of fossils have been found, must consult the 

 tables in the "Geological Manual" of De la Beche (3rd edit. 1833), and the Outlines of the Geology of 

 England and Wales, by Conybeare and Phillips, 1822. 



2 Every fossilist should visit the collection of Miss Mary Anning, at Lyme Regis, who, by her discoveries, 

 has so materially contributed to our acquaintance with the organic remains of the Lias, especially in the class of 

 those gigantic reptiles which characterize the formation. 



The Lias. 



1. Upper Lias Shale ; — (the Alum Shale of Yorkshire.) 



2. Marlstone. 



3. Lower Lias Shale. 



4. Limestone of the Lower Lias Shale. 



