H. F. Hall — Olacial Deposits of Llandudno. 511 



the bed that I have just described as the true Glacial Boulder -clay. 

 Where the layers of this (E^) stratified clay have opened by 

 weathering, they show very distinct ripple and rain marks. 



The next overlying bed consists of a development of about 20 feet 

 of irregular and false-bedded sands and gravels. I look upon it as of 

 the same age as the stratified grey clay la&t mentioned, being th-e 

 shore condition of the same period. A patch of about five feet of 

 green-coloured sand was to be seen in the Little Orme section, lying 

 above the red and yellow sands and gravels, and with thick beds of 

 red clay, false-bedded both with it and the yellow sands below. It 

 occasionally hardens into a thin bed of conglomerate, forming a 

 marked division on the cliff-face. On the west side of the Little 

 Orme the whole bed is cemented by carbonate of lime into a hard 

 conglomerate, masses of which are to be seen on the shore 12 to 20 

 feet in diameter. The upper portion is composed of finer pebbles 

 and sand, and forms a thin band of hard rock. 



After the shore condition, evidenced by the last-named beds, had 

 ceased, through the deepening of the water covering the old land 

 surface, a deposit of — 



Bed clay (D), which is everywhere of one character, has been 

 brought down by currents, bearing icebergs and icefloes, from the 

 more northern regions of Ireland, Cumberland, and Scotland, which, 

 probably from their higher lands, still sent down glaciers to the sea. 

 The uniformity of this deposit, the paucity of pebbles compared with 

 the bed F, the scarcity especially of scratched pebbles, and the fact 

 that it contains marine shells, as does also the (E) gravel bed, all show 

 that it has been formed under very different circumstances from the 

 glacial bed F' and, as it appears to me, at a time when glacial con- 

 ditions were modified by a warmer and more genial climate. 



The relative position of land and water was again altered by the 

 elevation of all the beds already considered, when the gravels and 

 sands (C) were deposited. 



These are best illustrated by the great ballast pit at Colwyn, the 

 present existence of which is explainable by its occupying nearly the 

 centre of a great valley of denudation in the Eed Clay, and to the re- 

 cess of the shore between the hills of Bryn Ewian and Colwyn Head, 

 the current passing eastward from one point to the other, not having 

 sufficient power to remove the pebbles, once rolled up in this quiet 

 retreat by the breaking waves. The bed is exposed to a depth of 

 fifty feet, but this is evidently short of the entire thickness. 



The last bed to which I have to call your attention, is a small 

 deposit of blue-black clay, without pebbles, which is exposed in the 

 Dyganwy section. That the underlying bed F, was covered with the 

 red clays (D), I think there can be no doubt; indeed, I conceive the 

 red clay to have covered the whole district in one great sheet, from 

 end to end. This must have been entirely denuded^ and the black 

 clay (F) exposed to a second denudation, which has resulted in the 

 thin bed of re-distributed black clay now referred to. Such is the 

 sequence of the beds. 



