NORTH-WEST OF ENGLAND AND NORTH AVALES. 101 



the Dee and Alyiij is a very high bank of shingle. None of the 

 stones were scratched. They consist of Silurian grits, Mountain 

 Limestone, felspathic and trappean rocks, greenstone, small pebbles 

 of granite, cherty limestone, syenite and Millstone Grit. On the 

 opposite bank and higher up the river, a landslip (August 1873) 

 displayed stratified sand with thin bands of gravel and, in some 

 places, fragments of coal. At one point there appeared to be seams 

 of peat ; but an examination showed they were composed of rounded 

 pieces of coal-shale closely packed together. I picked up fragments 

 of Cardium and Tellina ; but they were not plentiful. On the east 

 side of the railway between Wrexham and Gresford is a ballast-pit 

 (fig. 20) showing gravel, shingle, and boulders (c) lying upon strati- 

 fied sand (d). 



Fig. 20. — Section in Ballast-pit on the east side of the Valley 

 between Gresford and Wrexham. 



r 



i 



c. Gravel and shingle mixed with sand. 



d. Stratified sand. 



The bed of shingle and gravel was mixed with sand, and was about 

 25 feet high. There were some large granite boulders among it 

 mixed with stones common to the Lancashire drift and with local 

 stones and coal-shales. 



The local stones greatly preponderated. 



At Chirk we come upon the Dee again, and from the railway 

 viaduct can be seen a very great depth of half-rounded shingle which 

 has been cut into by the river on its right bank. 



Higher up the river than Llangollen and about Cor wen are great 

 hills of gravel and sand drift showing curved bedding ; these beds 

 are cut into cliffs on either side of the valley. Near Carrog station 

 the drift is very full of boulders. At Cynwyd station there is a deep 

 cutting in a buff-coloured clayey drift containing boulders. Near 

 Llandillo there is a good section of bedded sand and gravel. 



At Bala station there is a drift of angular, subangular, and slaty 

 shingle. Between Bala and Dolgelly, massive rounded boulders are 

 seen resting upon the rock. Here are also gravel mounds. There 

 are immense boulders in the gravel. The shores of Bala Lake by the 

 railway show gravel, shingle, and large boulders in the shallows of 

 the lake. 



General Observations on the Drifts of the Dee Basin. 

 The Boulder-clay of the estuary of the Dee is generally similar to 

 that of the Mersey. 



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