Charles Lapworth. 



xxxvii 



repeated many times ou itself by clean-cat faults, a striking illustration 

 of "sch'Uppen" or imbricate structure, common in the Alps and else- 

 where, but new to Britain. 



The relation of the Eastern or " Moine Schists " to the complex of 

 mechanically metamorphosed rocks' which lie below them was then 

 engaging much of his attention. He showed us that both groups had 

 been, so to speak, alive with movement, and speculated as to the 

 possibility of the latter representing a phase through which the former 

 had passed, but his views on this great question were not at that time 

 fully developed. The position he finally reached was summarised by 

 him as follows in a communication read at the Geologists' Association 

 on July 4, 1884, and subsequently published.* " I believe at present 

 that the great area of metamorphic schists of Sutherland and the 

 Central Highlands is, as a whole, neither Archaian nor Ordovician. The 

 Sutherland Gneiss — Arnaboll — is Archaean. The Sutherland Schist has 

 been manufactured since Silurian times. For all I know, there may 

 be large areas (in the Central Highlands, etc.), composed wholly of 

 Archaean (Laurentian) rocks, or of Cambrian or pre-Cambrian rocks. 

 When the metamorphism of the Highland area began I. think that it is 

 impossible to say, and may be always impossible. One thing seems 

 pretty clear to me — the so-called oldest beds of the Highland succession 

 of the Schistose Series of the N.W. Highlands are the newest in point of 

 time. The zone of intermixture and metamorphism (in Sutherland) 

 travelled to west from east, and the last beds (schists) manufactured are 

 those now in contact with the Assynt Series in Durness, Eriboll, and 

 Assynt " (p. 441). 



The subsequent work of the Geological Survey has not confirmed 

 these views, except so far as the occurrence of Archaean (Laurentian) 

 rocks among the Eastern Schists is concerned ; but, as stated in the 

 " Memoir on the Geological Structure of the North-west Highlands of 

 Scotland " (p. 600) : " The age and origin of the rocks that have been 

 mapped as Moine schists is a complicated problem which has not been 

 finally and definitely solved, but abundant evidence has been accumulated 

 to show that under the influence of the post-Cambrian movements rocks 

 of diverse age and origin have acquired a common type of structure, 

 and that true crystalline schists have been simulated if not actually 

 produced." 



The short time we were with Lapworth supplied us with a continual 

 succession of surprises. We did not know which to wonder at most, 

 the remarkable stratigraphy of a type hitherto unknown to Britain, or 

 the skill with which Lapworth, was unravelling it. He had been full of 

 energy and enthusiasm, relieved by occasional flashes of humour, during 

 the whole of the time we were with him ; but it was obvious that the 

 strain, both mental and physical, was very great and before the end of 

 * ' Proe. Geol. Assoc.,' vol. 8, pp. 438-442 (1885). 



