1 96 Physical Geography. 



sand, and, according to locality, of marine, estuarine, 

 fresh-water, and even terrestrial origin ; marine in Dorset, 

 Somerset, and Gloucestershire, partly passing into 

 estuarine and fresh-water strata in Northamptonshire, at 

 the very time, for example, that the marine sediments 

 of the Stonesfield Slate, had washed in among them, 

 from the neighbouring land, plants, insects, and mar- 

 supial mammals. Still further north, in Yorkshire, the 

 equivalent of great part of the Inferior Oolite actually 

 constitutes a coal-field, on a miniature scale, quite 

 comparable, in its sandstones, shales, underclays, and 

 beds of coal, to the broad and thick deposits of the 

 Coal-measures, and showing the same kind of alter- 

 nations of terrestrial and aquatic conditions, indicating, 

 repeated filling by sediments of a certain area, its 

 conversion into land, and its subsequent depression to 

 receive new accessions of sands and shales. 



These circumstances seem to me to agree, in a strik- 

 ing manner, with what may be surmised to have been 

 the state of the geography of the neighbouring lands. 

 In the south of what is now England the seas were 

 broad and comparatively shallow, during all the time of 

 the deposition of the Lower Oolites, and the islands 

 round which these seas flowed (including Wales) were 

 comparatively small. But further north we come to a 

 fragment of a much larger land, formed of Palgeozoic 

 rocks, that in those days formed a mountainous country 

 extending from the hills of Derbyshire far away to the 

 northern extremity of Scotland, and how much further 

 entire, or broken into islands, no man yet knows. In 

 spite of disturbances of upheaval of later date than 

 these Oolitic times, it may also very well have been 

 that this old land was much higher than the highest 

 Highland mountains of the present day, seeing the vast 



