Boulder- Clay. 38 7 



held lakes and tarns in the hollows of the mounds, but 

 now filled with peat. 



On the coast near Alnmouth, in Northumberland, 

 there is a large sand-bank overlooking the river with 

 intercalations of fine loamy clay. The sand contains 

 fragments of coal and other Carboniferous rocks, and in 

 the middle of the sand there lies a lenticular patch of 

 Boulder-clay, from six to ten feet thick, full of angular 

 ice-scratched stones confusedly mingled with the clay. 

 They consist of pieces of Carboniferous Limestone, 

 porphyries, sandstone, &c. the largest being about a 

 foot in diameter. 



Some miles south of Blyth there is a cliff forming 

 a promontory on the coast, made of boulder-clays, near 

 Seaton. It consists of two divisions, rarely separated 

 by thin lenticular bands of sand. The lower band of 

 greyish-blue clay is charged with large boulders, while 

 in the upper one, which is of a brown colour, the stones 

 are much smaller. The lower boulder-clay seems to 

 belong to the great glacier period that produced the Till, 

 and the upper band to a later glacial episode, and ex- 

 cept in the parting of sand, there are no signs of true 

 stratification. The large blocks, which are very 

 numerous, chiefly consist of Carboniferous sandstone 

 and conglomerate, which are often from one to two 

 yards in diameter. Blocks of Carboniferous Limestone 

 are fewer in number, as might be expected, for the 

 Boulder-clay lies on Coal-measures, while the Limestone 

 occurs more than twenty miles to the north and north- 

 west. Mingled with these are fragments of granite and 

 greenstone. 



On both banks of the Tyne, above Newcastle, there 

 are great banks of sand, gravel, and tilly clay, all 

 charged with ice-scratched stones of no great size. They 



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