246 C. LAPWORTH ON THE MOFFAT SERIES. 



Harkness, " On the Silurians of Dumfries," presented to the Geolo- 

 gical Society of London in 1850 *. 



The author clearly recognized the fact that the pj-ritous shales 

 are arranged in long lines among the barren greywackes, and gave 

 a brief description of several localities along the three parallel bands 

 of Hartfell, Prenchland, and Craigmichan, tracing these bands for 

 many miles through the district, and hinting their probable exten- 

 sion from sea to sea. Giving a general account of their peculiar 

 strata, their mineral character and fossils, he called especial atten- 

 tion to the remarkable similarity of the rocks of the three bands, 

 pointing out at the same time their excessive convolution, fracture, 

 and local metamorphism. Prom these facts he drew the most im- 

 portant inference that they were originally portions of one and the 

 same deposit. Their present position he attributed to three gigantic 

 faults running through the district parallel with the general strike 

 of the beds. The arenaceous strata among which they are imbedded, 

 he believed to be of the age of the Caradoc Sandstone of Siluria. 



The same year Sir Roderick Murchison, in his memoir " On the 

 Silurian Rocks of the south of Scotland" f, made several important 

 allusions to the strata of the district, some sections of which he had 

 himself hastily examined under the guidance of Prof. Harkness. He 

 expressed his willingness to accept Harkness's theory of the identity 

 of the strata forming the anthracitic bands ; but preferred to interpret 

 their geographical position on the hypothesis of great folds, the 

 upper arches of which had been denuded. At the same time he 

 emphatically assigned to the whole of the rocks of the district a geo- 

 logical position inferior to that of the Bala Limestone of North Wales. 

 He seems to have been especially struck with their shattered and 

 convoluted aspect, acknowledging that " all inferences drawn from 

 physical appearances must indeed be deceptive in so tortuous and 

 convulsed a region." 



The fossils of the black bands have been subsequently figured and 

 described by Messrs. Carruthers and Hopkinson, Prof. Nicholson, 

 and others ; and many references to the relationships and geological 

 position of the dark shales have been published by various geologists, 

 but no physical facts obtained within the district itself have hitherto 

 been brought forward in support of their conclusions. 



The task of determining the interrelationships of these enigma- 

 tical deposits, though in truth a very simple one, has been but 

 slowly accomplished. The scale even of the 6 -inch maps was soon 

 ascertained to be insufficient to allow of the insertion of all the 

 natural subdivisions of the dark shales ; and they had to be supple- 

 mented by enlarged sketch plans of all the more important expo- 

 sures. The caution requisite in proving and reproving every im- 

 portant point, stratigraphical and palseontological, in a region so 

 excessively disturbed has necessitated the accumulation of a mass of 

 confirmatory and supplementary evidence, sufficient to place wholly 

 beyond cavil all the data upon which our conclusions are founded. 



The determination of the geological age of the Moffat strata, and 

 * Quart. Journ. Greol. Soc. vol. vii. p. 46 et seq. t Ibid. vii. p. 139. 



