22 



had arrived before his work was broken off. These four or five 

 pages are so rich in conclusions and suggestions that it is hardly 

 fair to separate any portion from its context. The whole should 

 be read in the light of ' The Secret of the Highlands.' The following 

 quotations will show that Lapworth had followed the work to its 

 logical issue as to the age and nature of the ' Eastern Schists/ and 

 had also originated very definite views on the subject of dynamo- 

 metamorphism (32). 



*" The Sutherland Schistose series is composed of a complete 



intermixture of Archaean and Assynt rocks, the two series being 



so interfolded and interfelted together that they can never be 



separated in the field, but must be mapped simply as ' metamorphic.' 



" If I can prove my case, we shall find : f 



(1) That there is no recognisable chronological sequence 

 (or invariable succession of superposition) in the meta- 

 morphic Highland area corresponding to that among 

 the sedimentary formations (for the planes dividing 

 the truly metamorphic layers are not planes of de- 

 position, but planes of shearing and cleavage). 



(2) Many of its (the Highland) schists are composed of 

 Archaean materials (rocks) which have received their 

 present pseudo-bedded arrangement since Ordovician 

 times. 



(3) What proportion of its schists and gneisses is com- 

 posed of Archaean, sedimentary, or intrusive materials 

 respectively is in all probability an insoluble question. 



(4) Its gneisses may be either Archaean or (some) possibly 

 formed by intrusion (injection of plutonic rocks) in 

 later stages. 



(5) Its schistsmay be composed either of crushed Archceans, 

 crushed intrusives, or of a mixture of these with 

 sedimentaries. 



(6) Its (so-called) slates may be (according to the locality, 

 either normal slates or) crushed rocks not yet re- 

 crystallised, (and) of either Archaean, sedimentary, 

 intrusive, or of mixed origin." 



Some further details on the metamorphism of these rocks, 

 which he regarded as having been directed if not caused by pressure, 

 are given in a short paper read before the British Association in 

 1885, and published also in Nature of that year, while a summary 

 of the question and an outline of the " Deformation Theory of 

 Regional Metamorphism " was also published in Lapworth' s 

 edition of Page's ' Introductory Textbook of Geology/ which 

 appeared in 1888 (pp. 106-118). 



* 32, P- 438. t 32, pp. 441-2- 



