130 THE STErCTURE OF THE [vol. Ixxviii, 



Author considered the roots of his nappes to He. The ' Iltay ' 

 assemblage could be followed from Perthshire into Banffshire, 

 where the speaker had worked for several years. Away to the 

 north-west of the Banffshire rocks stretched Moine granulites for 

 70 miles to the thrust-ground of the North- West Highlands. 

 If the roots were in the thrust region, were they covered by the 

 thrusts ? The Moine region, the speaker held, carried nothing 

 suitable as roots for the Dalradian assemblage. 



The Author suggested that the ' Ballappel Foundation ' was 

 characterized by Eilde Flags and Glencoe Quartzite. But in 

 Banffshire the speaker found rocks of ' Iltay ' facies linked in- 

 separably on the west with a quartzite and granulites of Griencoe 

 and Eilde types. If the Banffshire Dalradian rocks were to be 

 included in the ' Iltay ' nappe, then so must a large part of the 

 Moine Series be similarly included. The phenomena of the Great- 

 Grlen Fault appeared to indicate to the speaker that the Dalradian 

 rocks overlay the Moine Series. But the Author, in his table, 

 showed the Eilde Flags at the top : the speaker disagreed with 

 that sequence. Correlation from Banffshire to Perthshire could 

 be made in some detail, and, if the Author's table for the ' Iltay ' 

 nappe were read from bottom to top, similar rock-types occurred 

 in Banffshire from west to east. But correlation could be made, 

 with equal chances of proving correct, from Banffshire into the 

 ' Ballappel Foundation.' The Banffshire rocks, from west to east, 

 were exactly like the Author's ' Ballappel ' table read from top 

 to bottom, and the speaker considered that this table should be 

 reversed, so as to place the Eilde Flags at the bottom. That com- 

 plicated still further the Ballachulish structures. 



The speaker believed in the reality of sliding or thrusting, but 

 he considered that the existence of nappes in the South- West 

 Highlands had not yet been demonstrated. 



Lord Cliffoed remarked that the Author's evidence concerning 

 the irregular folding of some of the strata in this part of Scotland 

 appeared to support a theory that the speaker had long held, that 

 folds and faults are mainly due to oceanic subsidences. Between 

 a line drawn from the Firth of Lome to the Moray Firth on the 

 north, and a line drawn from Morecambe Bay to Sunderland on 

 the south, there lies a tract of country that has been subject to 

 more strain and contortion than almost any other portion of the 

 woi'ld. - The folding of this part of Britain and the reversal of 

 strata in the manner described by the Author are results that one 

 would naturally expect. 



The Author, in reply, said that Dr. Flett's statement that 

 Scottish geologists were searching the Highlands everywhere for 

 analogues of Swiss structures might, perhaps, convey a wrong 

 impression. The speaker, as a matter of fact, developed his 

 interpretation of the Ballachulish district before reading the 

 Alpine literature or visiting the Alpine exposures. It had been 

 an added pleasure to find, on comparison of the two mountain- 



