21 



The facts could only be accounted for if inversion due to folding 

 or faulting had taken place. 



Attention was next given to the Durness Limestone, and it 

 is stated that it, *" though at first sight apparently homogeneous, 

 of great thickness and of very gentle inclination, is actually made 

 up of a few distinct lithological zones, repeated again and again 

 in a series of faults or inverted folds." 



Finally, he showed that the conglomeratic base of the quartzite 

 rested with visible unconformity upon a ' crystalline rock/ which, 

 though regarded by Nicol as an intrusive rock, was considered by 

 Murchison, Heddle, and Callaway as "an integral part of the 

 Upper [Eastern] Gneiss." Therefore rocks of ' Eastern type ' 

 were in position unconformably under the quartzite, and the 

 Eastern gneisses owed their apparently overlying position not to 

 superposition but to disturbance. 



The rest of this paper (' The Secret of the Highlands,' published 

 in three parts in March, May, and August, 1883) is occupied with 

 a discussion of the general and special principles of mountain 

 structure as developed by Heim in his ' Mechanismus der 

 Gebirgsbildung ' and illustrated with figures mainly taken from 

 that work and from Favre's ' Recherches Geologiques.' In intro- 

 ducing this branch of his subject, the author remarks : (" Many 

 of the points discussed in the following paragraphs will be found in 

 the truly magnificent work of Professor Heim upon the convoluted 

 rocks of the Alps. For those not hitherto published, I hold myself 

 responsible. The latter therefore are the only points open to the 

 objection of being original or heterodox, and the attempt here made 

 to summarise a few of the more essential principles of mountain 

 stratigraphy, and to apply them to the investigation of the High- 

 land region may be, perhaps, received as a first essay on one of the 

 most difficult and obscure departments of British geology." 



The second part of this revolutionary work was destined never 

 to be written. The hard work and harder living, coming on the 

 top of his other duties, resulted in a serious illness from which he 

 never really recovered sufficiently to regain the abounding health 

 and vigour which had rendered possible the immense volume and 

 depth of his earlier work. Before he had recovered health and 

 leisure {" the whole force of the Geological Survey of Scotland 

 laid siege to the Highland fortress " (as Professor Blake wrote in 

 1884)- 



The opportunity given, however, by the reading of Professor 

 Blake's paper, just quoted, at the Geologists' Association in July, 

 1884, was accepted by Lap worth to communicate, at the suggestion 

 of Mr. Teall, a few notes on some of the further results at which he 



* 30, p. 124. f 30, p. 195. 



{ Proc. Geol. Assoc., vol. viii, 1883-4, P- 22 - 



