﻿1851.] MURCHISON SILURIAN ROCKS OF SCOTLAND. 167 



The suggestion above alluded to, that the graptolitic and anthracitic 

 schists of Moffat belong to a group inferior to all the other fossil- 

 bearing strata of this region, may prove to be correct ; and if so, these 

 strata would represent the great schistose mass which lies beneath the 

 Llandeilo or Bala limestone of Wales. But this inference requires 

 confirmation. For, whilst a part of the researches of Professor Nicol 

 and myself would lead me to entertain this view, there must be more 

 exploration before I adopt it. If, for example, it be granted that 

 the Wrae and Stinchar limestones and all the fossil-bearing strata of 

 the northern zone be mineralized, metamorphosed, or attenuated on 

 the north flank of the highest hills, and that they really there con- 

 stitute an overlying mass, where in the numerous folds of the grey- 

 wacke to the south of such geographical axis do we find any represen- 

 tatives of the fossiliferous Lower Silurian of the Ayrshire and northern 

 bands ? And yet, if that were the arrangement, we ought to detect 

 some traces of such beds between the central axis and the Kircud- 

 bright strata which are the representatives of the Wenlock shale. 



The establishment of the lowest strata of the region has yet to be 

 determined by the discovery of the equivalents of the oldest Silurian 

 zone of Wales, the Malvern Hills, Scandinavia, and Bohemia. By 

 this I mean the band above spoken of, which is specially characterized 

 by the minute crustacean, the Olenus, and certain forms of Lingula * . 



The uppermost Silurian or Ludlow rocks are wanting in the South 

 of Scotland, and, if they were ever deposited, are probably now de- 

 pressed under the waters of the Irish Channel, forming a great undu- 

 lating trough between the South of Scotland and the North of Wales. 

 The evidences, however, which are left in the main land might lead 

 us to believe, that beds of the true Ludlow age had never been depo- 

 sited. Thus far is certain, that all those portions of the Old Red 

 Sandstone which constitute the two lower divisions of that system in 

 the North of Scotland have not yet been recognised in the southern 

 border counties, where the only representative of the Old Red yet 

 known is the conglomerate and sandstone with Holoptychius, which 

 constitutes the upper member of the system in the Highlands f. In 

 short, two-thirds of the Old Red or Devonian system and the uppermost 

 member of the Silurian are absent along the English border. Hence 

 we learn that at a very early period, the oldest deposits of the South 

 of Scotland had been raised into lands, and were not depressed, even 

 around their edges, until that subsequent period when the newer por- 

 tion of the Old Red was formed, to be followed by the Carboniferous 

 limestone, sandstone, and shale, and, with them, the associated coal 

 of Scotland. 



* Geologists can now study a fine succession of primordial life in the new and 

 most instructive Museum of the Government Geological Survey, wherein Sir Henry 

 De la Beche and his officers have also applied the term * Silurian ' to all the series 

 from the Lingula and Olenus beds to the Ludlow rocks inclusive. The Government 

 maps and sections are coloured on the same principle of classification and nomen- 

 clature. 



f See Mr. Hugh Miller's ' Old Red Sandstone,' p. 156 et passim. Also the 

 memoirs of Mr. W. Stevenson of Dunse, Proc. Geol. Soc. vol. iv. p. 29, and Quart, 

 Journ. Geol. Soc. vol. vi. p. 418. 



