Searles V. Wood, jun. — Sequence of Glacial Beds. 407 



counties of Inverness, Nairn, Moray, Banff, and Aberdeen, on the 

 North-east of Scotland, and penetrates the Highland valleys in all 

 directions, down to Perthshire and to Argyllshire on the West ; in- 

 osculating with and passing into the gritty obscurely stratified (and 

 sometimes Mwstratified) Boulder Drift of the mountain region ; and 

 that their overlay on the Aberdeenshire coast by red clay — a feature 

 which we did not detect throughout the mountain districts — is pro- 

 bably one of those peculiarities which seem to us incidental to 

 Glacial deposits, without possessing any classificatory value. These 

 Highland sands seemed to us to be probably the same as those 

 alternating with clays at Gamrie, on the Banffshire coast, which 

 yielded Mr. Prestwich some shells that were all of living species, 

 and were described by him in the Transactions of the Geological 

 Society upwards of thirty years ago •,^ all these sands, etc., appearing 

 to Mr, Harmer and myself to belong to the latest part of the Glacial 

 sequence, and to have been accumulated after the land-ice had dis- 

 appeared from Britain, and when the mountain districts of Scotland 

 and Wales formed a snow-clad archipelago of mountain tops which 

 was beset with floe ice ; and it is to the same period, I think, that 

 the sands of Moel Tryfaen, and those at high elevations (and pos- 

 sibly those also at low elevations that intervene between Boulder- 

 clays) in the North-west of England and Wales, belong. 



Mr. Binney adheres to the opinion originally advanced by him, 

 that although sand extensively intervenes between Boulder-clay in 

 Lancashire, that arrangement is not structural, but accidental ; and 

 he has recently published some notices of borings to corroborate this 

 view. The same opinion is entertained by Mr. Eome, Mr. Harmer, 

 and myself, respecting the sand and gravel beds in the Purple-clay 

 of Yorkshire ; and Mr. J. W. Judd (late of the Geological Survey), 

 who has quite recently been at work in the counties of Lincoln, 

 Kutland, and Leicester, also tells me that the sands and gravels in 

 those counties pass horizontally into Boulder-clay ; and he repudiates 

 altogether any classification based upon the alternation of Boulder- 

 clay with sand; while Mr. Wilson's description of the drift about 

 Eugby (Quart. Joum. Geol. Society, vol. xxvi. p. 192) seems to 

 suggest a similar conclusion. 



Under these circumstances, I should have begun to entertain a 

 doubt of the propriety of the classification of the Glacial beds into 

 Lower, Middle, and Upper, which I have for some years been en- 

 deavouring to substantiate, were it not for the distinct evidence of 

 this division upon far more striking grounds than the intervention of 

 sand between Boulder-clays, which the Survey of Essex, Suffolk, and 

 Norfolk, made by Mr. Harmer and myself (now, I am glad to say, 

 almost finished), has led us ; for this Survey has shown us that the 

 Lower Glacial formation of East Anglia (which is mainly not Boulder- 

 clay at all) was, prior to the accumulation of the sands and gravels, 

 which we term Middle Glacial, enormously denuded and swept 

 away, the part remaining being furrowed into valleys, some of them 



1 More shells from this locality have been since obtained, and are given in Trof, 

 Jamiesou's lists. 



