300 



LAPWORTH ON THE MOFFAT SERIES. 



1. All the black Graptolitic 

 shales of the Moffat district are 

 actually portions of one and the 

 same continuous deposit. 



2. They owe their repetition to 

 a series of subparallel folds, the 

 upper arches of which have been 

 denuded (fig. 25). 



3. They rise invariably from 

 below the surrounding greywackes 

 in anticlinal forms, the axes of 

 which are usually inverted. 



4. The deposit to which they 

 belong is consequently the oldest 

 rock-group in the Moffat district. 



5. This fundamental rock-group, 

 which is denominated by us the 

 Moffat Series, is composed of a 

 comparatively homogeneous as- 

 semblage of dark Graptolitic shales 

 and pale barren mudstones. 



6. Its collective thickness within 

 the limits of the present district 

 is about 300 feet, but its actual 

 base is nowhere visible. 



7. It falls naturally into three 

 primary divisions, each of which is 

 characterized by a special fauna, 

 made up almost wholly of peculiar 

 species. 



8. Each of these primary divi- 

 sions is again naturally subdivided 

 into several zones, individually dis- 

 tinguished by special mineralogi- 

 cal and palseontological character- 

 istics. 



In the light of these results the 

 difficulties hinted at in the early 

 part of this paper wholly dis- 

 appear. 



The varying width of each of 

 the longer shale-bands, its rapid 

 contraction near its extremities, 

 and its final disappearance, to- 

 gether with the peculiar boat-like 

 form of the shorter exposures and 

 their moniliform geographical ar- 

 rangement, were all facts utterly 

 inexplicable either upon the theory 

 that the black shales occurred on 



