P. Macnair — Altered Clastic Rocks of Scottish Highlands. 167 



GENERAL RANGE OF SUB-GENERA OF CHEIRURTJS IN TIME 

 IN EUROPE. 



VI. — The Altered Clastic Rocks of the Southern Highlands, 

 their Structure and Succession. 



By Petek Macnair. 



I. Introductory. 



IN the following paper I propose to give an account of some 

 observations upon the structure and succession of the rocks 

 of the Southern Highlands. By the term Southern Highlands 

 I mean that part of the Scottish Highlands lying immediately to 

 the north-west of the great line of fault separating the older rocks 

 of the former area from the younger Old Red Sandstone series of 

 the low grounds. 



The more detailed stratigraphical part of the work which I have 

 been enabled to undertake has principally been confined to the 

 central parts of Perthshire, and the sections illustrative of the 

 structure of the Southern Highlands will be principally drawn from 

 that source. But it will be evident to anyone upon the inspection of 

 a geological map that such sections will be more or less typical 

 of the whole series, seeing that the rocks strike in such a prevalent 

 north-east and south-west direction across the whole country. 



The principal object of the paper, then, will be to give an account 

 of the altered clastic rocks of the district, only mentioning in- 

 cidentally, and where it is necessary for making the sections clear, 

 the occurrence of igneous rocks. The nature of these clastic rocks 

 as altered sediments has now been long known, but the more 

 difficult points involving their structure, succession, and relationships 

 have not been at all understood ; and it is to these, then, I would 

 more particularly draw your attention, trusting to be able to throw 

 some light upon the somewhat obscure and difficult subject. 



