182 



tlie district must have been under the surface of the Chalk Sea, in 

 wliich Avere deposited the beds of chalk which we now find in the 

 Yorkshire ^^^olds, and which could not -well have had its shore 

 very far short of the crest of the Pennines. But whatever came 

 above the Kellaways Rock, OoHtes, Clialk, or what not, has been 

 stripped off to make sediment for ncM-er formations. 



Out of the Triassie and Jurassic rocks, then, have the main 

 physical features of Cleveland been carved. The beds were first 

 deposited, and then, after long ages, moulded into their present 

 form. 



The stunted fauna of the Permian bespeaks deposition in 

 land-locked inland seas. At the time of the formation of the 

 Trias, these seas Avere becoming shallowed and dried up. Then, 

 during the whole of the Rlijetic and Liassic periods, the land Avas 

 slowly sinking, and muds Ijrouglit l)y large and gently flowing 

 rivers, having a south-eastern course, were Ijeing de[)Osited in the 

 Cleveland area. There were many fluctuations it is true from 

 deeper to shallower and back to deeper again, and apparentlj^ 

 the minimum amount of depression occurred during part of the 

 l)eriod of the Middle Lias. Beds of oysters and cockles 

 flourished until they were overtaken by the drift of a current, 

 or an accumulation of sediment. Eight at the top of the series 

 we get, near Eavenscar, in a particular bed. an abundance of 

 Lingufa, a lamp-shell or brachiopod, which is at the present 

 day, I believe, a somewhat deep water form. But its presence 

 does not necessarily imply deep water, as it is a survival in 

 practically unaltered form of a very primitive type, and may have 

 been driven into deep Avater by the. greater competition for 

 existence in the shalloAver seas The large rivers brought doAvn 

 a good deal of timber, and fossil Avood is common in all the local 

 beds of Lias. In the jet rock this has often formed the basis 

 of jet. 



The loAver beds of the Oolite are fuller still of drift Avood, and 

 seem to have been deposited in the estuary of one or more large 

 rivers floAving from the north-Avest, "or possibly in a series of 

 channels or straits between the neighbouring islands."'^' But there 

 Avas apparently at this period a good deal of instability, and the 

 sea-bed of the locaHty sank and rose by turns. The "Dogger" at 

 the base of the Inferior Oolite contains a great many fragments of 

 fossils and rolled pebbles derived from Liassic beds, even doAvn to 



(1) C. Fox-Strangways. " The Jurassic Rocks of Great Britain " (Mem. 

 tieol. Surv., vol. I., 1892.) 



