26 8. V. Wood,jun. — American and British Surface- Geology. 



the Glacial features of North America and those of Britain mainly 

 to English beds, because I have for several years urged that none of 

 the Scotch beds can be older than the newer portion of the Upper 

 Glacial, viz. the purple clay of Yorkshire where the chalk debris 

 disappears, and the other chalkless clay to the north of it, which 

 consist probably of morainic material left by the ice after it had 

 receded from the lower ground of Yorkshire, overlain more or less 

 by clay and other beds of Hessle age. Looking at the mountainous 

 condition of Scotland, and that this part of Britain must have been 

 that to which the ice of the major glaciation clung latest in its reces- 

 sion, it seems to me that all the earliest part of the morainic material 

 which was coeval, not mei'ely with the chalky clay of East Anglia, 

 but even with all that in Holderness which contains any chalk 

 debris, must lie out beyond the present coast-line of Scotland, and 

 under the North Sea and Atlantic, having accumulated when the ice 

 of that part of the Glacial period to whose recession it was due 

 terminated beyond the present Scottish shores. When Tellina obliqua 

 and Nucula Cobboldice have been found in the Scotch Glacial beds, 

 there may be reason to regai'd the oldest part of the Scotch clay as 

 coeval with that portion of the English Upper Glacial which Bridling- 

 ton Cliff represents in the horizontal succession ; but until these do 

 so occur ^ I cannot see any reason for assigning an older date to the 

 Scotcli Till than above mentioned. Indeed it seems to me open 

 to doubt whether much of it belongs to the period of the first or major 

 glaciation, by reason of the improbability that beds of such character 

 as glacial accumulations could have resisted the degrading action of 

 any later ice. Such part only as by submergence during the minor 

 glaciation was protected from the ice of that glaciation can, it seems 

 to me, belong to what I term the Glacial ]3eriod. The well-known 

 case of Chapelhall in Lanarkshire appears to me to be an instance of 

 this ; for there the submergence of the Hessle period (which I have 

 described as commencing in the South with the insignificant depth 

 under which the Fen gravel accumulated, and increasing gradually 

 northwards) having attained upwards of 500 feet, the sediment 

 derived from the glaciers of the minor glaciation has been deposited 

 over mollusca which lived upon the surface of the submerged (and 

 so protected) moraine left by the recession of the ice of the major 

 glaciation. The occuri'ence of Eeindeer horns and some few other 

 mammalian remains in Scotch beds, seems also to receive satisfac- 

 tory explanation by reference to this minor glaciation. 



Mr. Geikie, in the 2nd edition of his work, seems to feel the 

 difficulty of earlier Glacial deposits having in Scotland escaped the 



1 Latitude can have nothing to do with the presence of these shells, because, among 

 the derivative fossils of either late Crag, or early Glacial age, found by Mr. Jamieson 

 in gravels capped by Boulder-clay, near Aberdeen, which he sent me for examination, 

 there was an undoubted fragment of Nucula CobboldicB, showing that this species had 

 once lived there ; and Tellina obliqua has been found associated with the other 

 Upper Crag Tellens, in beds in Iceland, whose fossils correspond with the later Crag 

 beds. If, as I suspect, most of the ice-formed beds of Scotland belong to the minor 

 glaciation, the ice of which destroyed the preceding beds as far as it extended, the 

 derivative molluscan remains found by Mr. Jamieson probably constitute part of the 

 wreck of the deposits of the first or major period of glaciation in that country. 



