Gr. A. Kin AH AN — On Boulder-clays and their Gravels. 209 



but in such eases never extending through them, as is proved by the 

 railway cuttings. A very instructive case occurs at Eedhill, to the 

 west of Boyle, Co. Eoscommon, and is described in the Greological 

 Survey Memoirs by Mr. Cruise. 



In some places, as in the vicinity of Pomeroy, Co. Tyrone, an 

 angular, shingly drift has been called " upper boulder-clay," 

 although there is not a particle of evidence to suggest a glacial 

 origin; while elsewhere high level gravels, as on Slieve Grallion 

 Carn, Co. Londonderry, are said to be of the same age as the 

 gravels of the low neighbouring plains, and as they are under 

 glacial or glacialoid drifts, are said to prove that the latter are 

 those so-called "middle gravels"; although it must be evident to 

 anyone who examines them thoroughly, and carefully considers 

 the subject, that the higher gravels must be quite distinct, and 

 are probably older than the lower ones. 



The result of many years' minute examination and considera- 

 tion of the drift accumulations in various places in the United 

 Kingdom, combined with a study of the published descriptions of 

 drift sections by numerors observers there and elsewhere, would 

 lead me to suggest — 



First — That some of the gravels and other stratified drifts 

 under glacial drifts may be younger than the overlying deposits. 



Second— Thdii many of the sands and gravels in the till and 

 moraine drifts are probably younger than the materials now lying 

 over them; and 



Third — That gravels, sands, and other stratified drifts contem- 

 poraneous with the allied glacialoid drift, must in general be 

 younger th&n the associated glacial drifts; the exceptions being 

 few and rare. 



As to the first : in certain places the till or moraine"drifts may 

 have accumulated over deposits of gravel or such like ; but in other 

 places it seems highly probable that the gravels now found under 

 them were due to the water formed in the ice before and during 

 its final melting, producing streams under the glacial drift, thereby 

 washing portions of it into gravels and sands. This is specially 

 suggested by finding boulders in places in these accumulations, 

 while the stratification is distorted as if by currents curling round 

 the boulders, or by the roof falling in ; also, many of those who 



