388 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 24, 



man's head ; but as we go to the north-west, they increase both in 

 number and in size. The nearest granitic rock in that direction is 

 at Cruachan, about sixty miles to the north-west of Airdrie. 



In the Till itself, organic remains are so rare, that it has been con- 

 sidered by some geologists as altogether destitute of them. There 

 are, however, perfectly well-authenticated instances of the bones of 

 the fossil elephant being found in it, and upon one occasion I found 

 broken and water-worn fragments of shells irregularly dispersed in 

 it*, amongst which I recognised the massive hinge of the Cyprina 

 Islandica, Linn, sp., and the stem of a large species of Balanus, ap- 

 parently the same as that figured by Sir Charles Lyell in his paper 

 on the Changes of Level in Sweden f. Both species abound in the 

 pleistocene beds, but neither of them is found in the immediately 

 adjoining sea. The shells lately discovered in the Till by Mr. Cleg- 

 horn, at Wick and at Thurso, are precisely in the same state as those 

 discovered by me, namely broken and water-worn. I may add, that 

 they have the same arctic character, for amongst them I observe the 

 Tellina proxima or calcarea, the Astarte borealis, Linn. sp. ; and 

 the Astarte Withami of my catalogue, so named because the shell was 

 sent to me from Bridlington by the late Mr. Witham of Lartington. 



We may conclude from the facts now brought before the Society, 

 that the Till, and the stratified beds which lie immediately below and 

 above it, all belong to the same geological period — to that which im- 

 mediately preceded the present, and which has been named by Prof. 

 Edward Forbes the Glacial epoch. 



I may add, that Mr. Russell states that after passing through the 

 shelly bed of brick clay, he came again to the Till ; thus proving in- 

 disputably what has always been suspected, that there has been 

 more than one deposition of the Till or boulder clay. 



Notice of the occurrence of Marine Shells in the Till. By 

 John Carrick Moore, Esq., Sec. G.S. In a letter to James 

 Smith, Esq^., of Jordan Hill, F.G.S. 



" I HAVE two facts to communicate, which have come within my own 

 observation in Wigtownshire, and which will interest you who have 

 paid so much attention to pleistocene geology. 



" 1st. After dihgently hunting the boulder clay, which usually is 

 found to contain only fragments of shell, and that sparingly, I suc- 

 ceeded in finding one perfect valve of Astarte compressa, Montag. sp. 

 The spot where I found it is on the west shore of Loch Ryan, about 

 two miles from Stranraer; it was imbedded in the genuine Till or 

 brown sandy unstratified clay, with blocks of transported rocks inter- 

 spersed through it. 



" 2nd. Reposing on the Till, patches of a distinct clay containing 

 no gravel or boulders, occasionally occur in Wigtownshire. On one 

 of these is erected the Culhorn Tilework, within half a mile of Stran- 



* See my paper in Wern. Memoii's, vol. viii. 

 f Philosophical Transactions for 1835. 



