On the Geology of Moffat, Dumfriesshire, 387 



or cream-coloured shales have been quarried for roofing slates 

 at the head of Corrieferan Glen. They exfoliate in the planes 

 of stratification, and have no true slaty cleavage. They are 

 thick and heavy ; and though very durable, the bad roads, 

 and the working expenses of a quarry in such a locality, have 

 caused them to be neglected. 



The general directions of the strike of the Silurian strata is 

 east and west ; and the dip, when not vertical, is always at a 

 very high angle — 70° or more. Professor Nicol has noticed 

 in Peeblesshire what may be observed in this district also, 

 that the direction of the dip is towards the interior of the 

 mountain chains, being south on the north, and north on the 

 south side. The few scattered records of the strike and dip 

 of the Silurian strata of the south of Scotland seem to be in- 

 sufficient to establish a satisfactory theory of their structure. 

 This will follow only after the observing and recording on a 

 good map a large series of observations throughout the country 

 from St Abb's Head to Portpatrick, and from the Pentlands 

 to the Solway. The theory of Professor Harkness, adopted 

 by Sir Roderick Murchison, does not seem to meet the facts. 

 Many of the additional localities for graptolitic shales, dis- 

 covered within the last ten years, do not fit into his three 

 faults. Nor does it seem possible that strata, vertical, or so 

 highly inclined, could repeat themselves in a series of faults. 

 Faults cannot tell, except on more or less horizontal strata. 

 It is more in accordance with my own observations and those 

 recorded by others, to believe that the position of the strata is 

 owing to enormous flexures produced in a manner similar, but 

 not so regularly, to what has been observed and ably ex- 

 pounded by the Professors Rogers as occurring in the Appal- 

 achian Mountains. 



Permian Sandstone. 

 The red sandstone is a very friable rock, the quartz 

 granules of which are held together by a ferruginous cement. 

 Its structure is frequently very coarse, forming a sandstone 

 conglomerate, containing numerous generally angular frag- 

 ments of the Silurian rocks. At Newton it has a fine and uni- 

 form grain. A few years ago a large quantity was quarried at 

 this place for building, but it was so friable that it could not 



