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- 
lachian 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 
