80 Tranfiact'iniw. 



view a few others agree with Wahlenberg. In 1839 Sir Roderick 

 Murchison described and figured in his Silurian System three 

 species of Graptolites. He was of opinion that Graptolites show 

 most affinity with the living Pennatulidte. We are indebted to 

 Professor Sedgwick for the first account of the rocks of the 

 Moffat district. In his memoir, " On the Geological Structure 

 and Relations of the Frontier Chain of South Scotland," which 

 was read at the British Association at Glasgow in 1850, he 

 classed the rocks of the Soutliern Highlands into five successive 

 formations. The oldest and lowest of these formations he called 

 the Moffat group, embracing the greater part of the strata of the 

 district. It was explained as " a great thickness of arenaceous 

 rocks, in which pyritous and graptolitiferous schist abounds to 

 such an extent that the arenaceous beds become sometimes sub- 

 ordinate to it." In the same year he also described and figured 

 twelve species of Graptolites from the anthracitic shales (Upper 

 Llandeilo) of Dumfriesshire. But there can be no doubt that 

 the most valuable paper which has as yet been published upon 

 the rocks of the Moffat district is the memoir of Professor 

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

 Geological Society of London in 1850. The author clearly 

 adopted the view that the Graptolitic shales run in long lines 

 among the unfossiliferous greywackes, and gave a short descrip- 

 tion of several localities along the three parallel bands of Hart- 

 fell, Frenchland, and Craigmichen. Following these bands for a 

 number of miles through the district, he assumed their probable 

 continuance from the one sea to the other, and seemed to consider 

 that the great disturbances and upheavals which these rocks 

 sustained were caused by three gigantic faults ; but I find no proof 

 of such faults running through the district. Sir Roderick Mur- 

 chison, the same year, in his communication " On the Silurian 

 Rocks of the South of Scotland," made some important state- 

 ments upon the strata of the district — some sections of whicli he 

 had hastily examined under the guidance of Prof. Harkness — 

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

 identity of the strata forming the Graptolitic bands, but he pre- 

 ferred to interpret their geographical position on the hypothesis 

 of great folds, the upper arches of which had been denuded. 

 This view is the one now generally accepted. The dark mud- 

 formed shales that are associated with the Greywackes, and in some 

 parts highly anthracitic, are evidently the remains of an ancient 



