C. LAPWORTH ON THE MOFEAT SERIES. 265 



of these anticlinals is a faulted one, a portion of the inverted leg of 

 each being lost. 



It is interesting to note how the degree and intensity of this 

 inversion decreases in proportion as we pass outwards from the 

 chief anticlinal line ; and, as we shall see in the sequel, the section 

 is an admirable illustration of the general structure of the whole 

 of the Moffat district. 



The beds exposed and their interrelations can be understood from 

 the figure (fig. 4). The fourth anticlinal is the only one which calls 

 for description in this place. Its strata, in addition to yielding all 

 the fossils of the Lower Birkhill Shales, include also an almost un- 

 broken mass of the Upper Birkhill beds. Their fossils are beautifully 

 preserved, and embrace Bastrites maximus, Monograptus turrieu- 

 latus, M. Halli, and other forms peculiar to the very highest band 

 of the Birkhill Shales. 



Conclusion* 



It is evident from the preceding description that our conclusions 

 regarding the sequence and fossils of the Moffat Shales, deduced 

 from our study of the rocks of Dobb's Linn, are perfectly sound. 

 The succession in the present locality is easily interpreted by their 

 aid, and the inferiority of the shales and mudstones to the great 

 greywacke group in which they are imbedded is amply demonstrated. 

 AVe have here gained a much fuller insight into the thickness and 

 lithological characters of the Glenkiln Shales, which are seen to have 

 an importance which would never have been suspected from the in- 

 significant exposure of these beds at Dobb's Linn, and we are now 

 in a position to commence the study of the numerous black-shale 

 bands of the district. 



§ II. Description of the Bands of Black Shale to the South of the 

 Moffat- Yarrow Valley. 



(a) Black Bands to the South-west of St. Mary's Loch. 

 (Plate XL, Map No. II.) 



Nowhere in the Moffat district are the bands of black shale so 

 continuous, their strata so little dislocated or confused, or their 

 fossils so well preserved as in the high ground which lies to the 

 south-west of St. Mary's Loch, and forms the watershed between 

 the upper portion of the river-basins of the Ettrick and Yarrow. 

 Four distinct black bands are here apparent, about half a mile apart, 

 running approximately parallel with each other and with the main 

 longitudinal valley to the north. Numerqus streamlets descend the 

 opposite slopes of the watershed, generally at right angles to the 

 black-shale bands, but occasionally flowing over them for some dis- 

 tance. These furnish us in many instances with several exposures 

 of the component strata of each band at different points along its 

 course. In this way we obtain a large amount of confirmatory and 

 supplementary evidence, which no one who is acquainted with the 



Q. J.G.S. No. 134. i 



