206 COOKE : WORK FOR LINCOLNSHIRE GEOLOGISTS. 



show that the greater part of the rock of which they are composed is 

 made up of the fossilized remains of creatures of a most varied 

 character. In the marine beds are to be found the remains of 

 cephalopods, corals and shell-fish intermingled with the bones and 

 teeth of sea-monsters such as could only have existed in the waters 

 of salt-oceans of considerable extent ; and they offer both in the 

 creatures entombed in them, as well as in their structural pecu- 

 liarities, unequivocal evidences of their origin, and of the physical 

 conditions under which they were formed. 



And then passing on to the integument of Boulder Clays, 

 agglomerates, breccias, loams and old river-gravel with which many 

 parts of the surface of the county are covered, we see in their fauna 

 or the physical features that they exhibit, evidences of the 

 vicissitudes of changes in climate, in topography and in animal life 

 which Lincolnshire has undergone in what are, geologically speaking, 

 comparatively recent times. But to pass on from the general to the 

 particular. The problems, on which I now propose to dwell, admit 

 of a threefold classification, viz., structural, genetic, and correlative. 



The first of these have to do with the stratigraphy of the region ; 

 and they are therefore the most important. In most parts of the 

 county no difficulty will be experienced in making out the order of 

 succession of the rocks ; and the work will be greatly facilitated, too, 

 by the entire absence of the complex foldings which are so common 

 a feature in the rocks of neighbouring counties. This order has, in 

 most cases, been made out and satisfactorily explained in the Survey 

 memoirs ; but there still remains much that requires investigation and 

 explanation. For example, in Dorsetshire and other parts of England 

 where the Kimmeridge and the Oxford Clays are largely developed, 

 these two beds are separated by a series of grits and limestones, 

 known as the Corallian. In Lincolnshire this series appears to 

 have no representative in the northern portions of the county, as 

 around Brigg and Wrawby the Upper and the Lower Oolites are 

 found merging the one into the other; but the evidences do not 

 appear to be so conclusive in the sections that occur from Bardney 

 to Horncastle. 



The determination of the line of demarcation between these two 

 formations is rendered the more interesting by reason of the marked 

 absence of any lithological differences between them ; and therefore 

 in most cases lithology has to be ignored and dependence placed on 

 the two oysters Ostrea deltoidea and Gryphma dilatata, which 

 respectively serve as the characteristic fo ils of the two formations. 



This is a most interesting point, and further researches in other 



parts of the county would no doubt help to throw more light upon it. 



Naturalist, 



