On the Agricultural Geology of England and Wales. 463 



Eden to Carlisle, where they are mixed with erratic blocks 

 which have crossed the Sohvay Frith. They have been drifted 

 southwards in immense quantities by Lancaster and the narrow 

 tract between the mountains and the sea, crossing the lines of 

 the Lune, Ribble, Wyre, Weaver, Mersey, and Dee ; and 

 spreading over the plain of the new red sandstone in Cheshire 

 and Shropshire, into the valleys of the Severn and the Trent. 

 Throughout this large area they are mixed with other granitic 

 fragments, of various sizes, which may be referred to the Isle of 

 Man and the Mourne mountains in Ireland, and which are partly 

 on the surface, partly imbedded in deep strata of sand, gravel, 

 and clay. Large erratic blocks of northern origin are lodged, in 

 great numbers and at great heights, on the northern flanks of the 

 Welch mountains. Granite blocks are also found on the N.W. 

 skirts of the chain, as far as Bagillt; but from, that point they 

 diminish in size, and S. of Conwy the Cumbrian and Scottish 

 granites give place to smaller granitic fragments, most of w^hich 

 appear to have come from Wicklow and other parts of Ireland.* 

 They are associated with fragments of other rocks which indicate 

 transport from the N.W. Among the most remarkable of these 

 is the hard chalk of the county of Antrim, of which a continuous 

 stream has been traced, in Ireland, from its source as far S. as 

 Wexford. 



The tail of this stream of Antrim detritus appears to have 

 caught the Welch coast, for we have found it in the boulder clay 

 of the extreme point of Caernarvonshire, and much further to 

 the south, between Newport and St. David's Head in South 

 Wales. 



Erratics of the East of England. — The erratic blocks from the 

 lake district of Westmoreland, which were traced across the 

 Penine chain to the sea coast of Yorkshire, have there met 

 another stream of granitic and other crystalline blocks, which 

 must have been derived from the east of Scotland and from 

 Norway, these being the nearest points at w^hich such rocks 

 exist in place. This forms the commencement of that district of 

 erratic tertiaries, described in the seventh volume of the Journal 

 of the Royal Agricultural Society, as extending, with some 

 alluvial interruptions, to the valley of the Thames. In the 

 valley of the Waveney erratic blocks and bouldered oolitic fossils 

 abound, and, from their increasing prevalence westward, there 

 can be no doubt that they were derived from that quarter. Boulder 

 clay, with granitic, oolitic, and other foreign detritus of various 

 kinds, extends from Norfolk through Cambridgeshire, Suffolk, 

 and Essex, to the northern side of Hampstead Hill, where 



* Joiirn. Geo]. Soc. Dublin, vol. i. part iii. p. ISO, 



