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XXVI— NOTES OlSr THE CLASSIEICATION OF THE BOrLDER- 

 CLAYS AND THEIE ASSOCIATED GEAYELS. By 

 G^. H. KINAHAN, M. E. I. A. 



[Read, January 21, 1884.] 



The phenomena to be observed in connexion witb the boulder- 

 clays and their associated gravels, &c., especially in Ireland, are 

 far from having been satisfactorily explained; it may therefore 

 be allowable to make some remarks on them. 



It would appear as though the present confusion is in a great 

 measure due to observers rushing to conclusions without sufficient 

 and careful examination or thought, and also forgetting to com- 

 pare the deposits that they would explain with those that are being 

 laid down at the present time. 



There are three classes of more or less similar drifts, which are 

 commonly called boulder-clay : — 



1st. The Till, or the Lower Boulder-clay. 



2nd. Moraine Drift, or the Upper Boulder-clay. 



3rd. GrLAciALoiD Drift. 



Nos. 1 and 2 are true glacial drifts ; while No, 3 was originally 

 glacial drift, but has subsequently been re-arranged, either by water 

 or atmospheric agencies. Associated with all, but especially the last, 

 there are gravels, sands, with brick and " book" clays, or, under cer- 

 tain circumstances, marls. These occur sometimes above, sometimes 

 below, but more often in different intermediate positions, while in 

 general the relative positions of these different drifts are supposed 

 to indicate their relative ages. This, however, appears to me to 

 be " not proven," as the facts observed by Clarence King on the 

 Western Pacific slopes, and by Hayes and others in Arctic and 

 Alpine regions, combined with what can be studied as taking place 

 at the present day in Grreat Britain and Ireland, would suggest 

 otherwise. 



Prior, however, to going further into these subjects, we may 

 give a resume of the principal sections in Ireland that are said to 

 afford conclusive evidence of there having been upper and lower 

 glacial drifts, with " middle gravels " of an intermediate age be- 

 tween them. 



