112 T. M. EEADE OjS" THE DKIET-BEDS OF THE 



At Llanfairfechan, on the banks of the river, at about 100 feet 

 above high -water mark, there is a section of Till, containing large 

 angular, subangular, and rounded stones imbedded in a matrix of 

 cream-coloured clay; some of the stones, I noticed, were faintly 

 striated, and others ground flat. They appear to be all local 

 felstones, porphyries, and greenstones. The river, at times, is very 

 furious, having a rapid descent, and carries down large blocks of 

 stone. A few years before 1874 it piled up a mass of stones against 

 the railway-bridge and broke one of the cast-iron girders. On the 

 top of the Till was a patch of gravel and shingle; considerably above 

 this and on the western extension of a moraine-like mound is a 

 gravel-pit (b, fig. 27) showing current-bedded and contorted lamina- 

 tions like the gravel-pit which will be described at Bangor. The 

 mound is very steep on the north and west sides. Crossing this 

 gravel mound we came upon the river again, which has cut cliffs 

 (E, fig. 27) I should judge to be about 80 feet high out of a deposit 

 of current-bedded sand, gravel, and shingle which fills the valley. 

 Higher up the river this deposit appears to rest upon the Till ; and 

 the same appears to be the case lower down (as at F, fig. 28). There 

 is an immense deposit of sand, gravel, and shingle in this valley. 

 I could find no shells in any of these deposits. 



Fig. 27. — Section above Llanfairfechan. 



Gpra.velvil. 



Fig. 28. — Section of Cliffs lower down the River than fig. 27. 



At Penmaenmawr, in an excavation made to repair the sea-retain- 

 ing wall of the railway, I noticed, lying upon the slate rock, a brown 

 clay in which was imbedded a boulder of felspar porphyry ; over this 

 was a thin bed of green clay, then a bed of yellow clay. 



Ascending the valley at Aber, we find that the gorge where two 

 streams meet is swept pretty clear of Drift ; but above this there is 

 a great deposit of Drift, which rises rapidly, apparently in a series of 

 benches, towards the cascade, where the Drift becomes very stony, 

 being mostly shingle and boulders of local rocks — porphyries, green- 

 stones and felstones. All the way to the head of the valley the 

 rocks are Silurian shaly slates. There are a great many greenstones 

 and other boulders of great size lying on the sides of the valley, 

 usually where it is denuded of Drift ; but none that I saw were 



