416 MR. BEEXARD SMITH ON THE [Sept. T912, 



middle of the cliff, and occasional boulders of Criffel Granite 

 occur as far south as Towuend Bank. The red loamy Upper 

 Eoulder Clay ends at the southern extremity of Townend Bank ; 

 while red sands and gravels appear at the top of the cliff, and 

 extend nearly to its base, which consists of reddish boulder-clay. 

 The stratified false-bedded sands are of various degrees of fineness 

 -and colour, and have variegated sandy loams and clays interbedded 

 with them. 



In Silecroft brickyard there is an exposure of about 12 feet of 

 salmon-tinted loamy Lower Boulder Clay, containing very few 

 stones. In addition to a few volcanic boulders, there were slate 

 and coal fragments, some well-striated fine grits, and a small 

 boulder of Criffel Granite. At the clay-pits east of Whitriggs 

 Close, Haverigg, the section consists, in the lower part, of a red 

 loamy clay with small stones and boulders and a few sandy laminae. 

 The upper 12 feet is chiefly yellow sand, with streaks of clay, 

 beneath a capping of dull chocolate-coloured clay with a few stones. 



VII. The Loaver Boulder Clay. 



(I) The Coast-Sections. 



It thus appears that Mackintosh's three divisions of Lower 

 €lay, Middle Sands, and Upper Clay, although one member or 

 another may be missing, hold good in the main ; but the lateral and 

 vertical variations in character, and the changes in level of the 

 drifts, are probably much greater than he imagined, and the facts 

 are not compatible with his theories concerning their mode of 

 formation. The passage, for example, of a lower brown till, 

 which rises above high-water mark at Gutterby Banks, into a 

 reddish loamy clay within a space of a few yards is more suggestive 

 of the action of an ice-sheet that has picked up materials of 

 diverse character and incorporated them in its ground-moraine, 

 than of deposition in water. The whole series, as Mr. Lamplugh 

 has pointed out,^ is strikingly similar to that of the Extra-Insular 

 Drift of the Isle of Man described by him in these terms : 



' the whole [that is, the three divisions] are so intermingled and so inter- 

 changeable that, so far as the beds above sea-level are concerned, we can 

 scarcely escape from Mr. [P. R] Kendall's conclusion that the Manx drift 

 forms one great irregular series.' 



After expressing the view that both the Extra-Insular drift and 

 the Local drift of the Island were practically contemporaneous, 

 -and both the product of land-ice, he concludes that {op. cit. p. 356) 



' Whatever explanation is adequate for the Isle of Man will be capable of 

 wide application ' 



to this and other areas. 



The Middle Sands and Gravels I consider to have been formed 

 during the waning of the ice-sheet, preceding a slight advance 



^ ' The Geology of the Isle of Man ' Mem. Geol. Surv. 1903, p. 335. 



