260 C> LAPWORTH ON THE MOFFAT SERIES, 



rally overlying Birkhill and Gala beds, which have been forced in- 

 wards upon them from opposite sides by the excessive lateral 

 pressure. 



The section of the North Cliff in the present locality is a good 

 instance of this phenomenon. The Birkhill Shales, which bound 

 the central wedge of Hartfell Shales &c. included between the con- 

 verging east and west faults, have been thrust inwards upon the 

 lower and narrower portion of the wedge, forcing it upwards, and 

 at the same time giving its component strata the characteristic 

 radiating dip. 



§ I. (b) Description of the confirmatory sections of Craigmichan 

 Scaurs. (Plate XIII. Plan A.) 



Before applying the results deduced from our study of the rocks 

 of Dobb's Linn to the investigation of the shattered beds of the 

 Moffat Series exposed along the various lines of black shale, it will 

 be more satisfactory if we first put them to a crucial test by endea- 

 vouring to unravel at least one additional section in which the 

 whole sequence of the beds is exposed. The only section suited for 

 this purpose is that of Craigmichan Scaurs, which occurs on the 

 western flank of Capel Law (2300 feet) at the head of Selcoth Burn, a 

 small stream falling into the Moffat water about six miles below 

 Birkhill. 



The rocks of the Moffat Series at this locality are shown in a re- 

 markably rugged gorge, about a mile in length, bounded on both sides 

 by steep slopes, partly formed of naked cliffs of black shales, partly 

 of mounds and trails of their weathered fragments. The southern 

 wall of the gorge resembles that of Dobb's Linn. It is black and 

 precipitous, but nowhere reaches a hundred feet in elevation. The 

 northern wall is actually the flank of the mountain of Capel Pell, 

 and shows a naked and almost vertical face of dark shale and mud- 

 stone, five hundred feet high, affording the most magnificent section 

 of the Moffat Series in the south of Scotland. 



Everywhere within the gorge itself appear the black and varie- 

 gated Moffat Shales. On the higher portions of the bounding cliffs 

 are seen the thick greywackes and flagstones of the Gala group. 

 At one spot the latter visibly descend the southern cliff for some 

 distance, affording us an excellent starting-point from which to 

 commence a study of the succession. 



(a) Section along line A-B. (Fig. 2.) 



Immediately we descend into the dark shales below the grey- 

 wackes, we observe at a glance that we have no longer to deal with 

 slightly disturbed and highly fossiliferous beds like those of Dobb's 

 Linn, but with strata contorted and shattered, and so greatly altered 

 that their fossils are almost wholly obliterated. Here and there, 

 however, we observe certain grey bands with white lines dipping 

 below the grits ; and searching carefully right and left in the less 



