﻿1851.] MURCHISON SILURIAN ROCKS OF SCOTLAND. 161 



the last Meeting of the British Association at Edinburgh, the oldest 

 strata in the South of Scotland*. But the subject calls for closer 

 researches before the question can be decided, and before we can class 

 the Moffat and Dumfries group in the lowest division of the series. 



In the immediate neighbourhood of Moffat, I made one detailed 

 section of a few miles across the strike on another parallel (partly in 

 company with Mr. Harkness), which also exhibited a very great per- 

 sistence in a northerly dip ; i.e. from the Craigie Burn and Hunter 

 Heck over a hill marked by an Ordnance pole and across the French- 

 land Burn to the hills on the north. In this space grey and purple 

 flagstones with Annelids ? or worm-like bodies, not unlike some of 

 those (Myrianites) in the Lower Silurian rocks (formerly erroneously 

 considered by myself to be Cambrian) near Lampeter in S. Wales, 

 are found in the plantation quarry above Hunter Heck. These beds 

 dip 72° to the N.N.W. under a higher summit, in part composed of 

 reddish thin tilestones and of overlying masses of strong-bedded flag- 

 like greywacke. These are followed by shale or schist, occupying a 

 moory depression, and the hard greywacke, being renewed in the 

 slopes, is succeeded by a band of jet-black, fissile, anthracitic schist, 

 very pyritous in parts, and exhibiting Graptolites, as well as anthra- 

 cite. The occurrence of anthracite in certain schists of the clay-slate 

 of Dumfriesshire was cited by General Diromf many years ago. Such 

 natural appearances as are seen in this Frenchland Burn, viz. the 

 black schist and anthracite beds, or * ampelite ' of the French, have 

 naturally led persons, ignorant of geological succession, not only to 

 hope for coal-seams, but even to open works J. 



I allude to this partial section east of Moifat, to show the impos- 

 sibility, in this troubled region, of estimating the true order and suc- 

 cession of the strata by any appearances of the strike and dip on one 

 line of traverse only. Thus, if the geologist proceed a little to the 

 east of the sectional line, he would find the graptolite-schists appa- 

 rently overlaid by a mass of strong-bedded, hard greywacke-grit, 

 dipping 70° to the N.N.W. ; but, in turning westwards a few hundred 

 paces and in descending the same Frenchland Burn, another scene 

 awaits him. There, beds of purple greywacke-flag, schist, glossy 

 shillot, and pyritous shale are seen overlying an anthracitic course of 

 about eight feet thick, the whole supported on strong-bedded grey- 

 wacke-grit, which, rolling over, is followed in the descent of the stream 

 by a similar succession of anthracite, schist, greywacke, &c, dipping 

 S.W., instead of to the N.W. In truth, this turn of the Frenchland 

 Burn is near the spot where igneous rocks, intruding into the strata, 

 have greatly modified them, and have given rise to those accumu- 

 lations of fractured, contorted, and aluminiferous or pyritous schists 

 in which the mineral waters of Moffat take their rise. I could not 



* Professor Sedgwick now entertains the same view, as appears in the printed 

 abstract of his verbal communication at Edinburgh, which has appeared since this 

 memoir was sent to press. See Rep. Brit. Assoc. for the Advancement of Science, 

 1850, Trans, of Sections, p. 104. 



f General Dirom's observations are appended to an old map of Dumfriesshire, 

 now difficult to be had, although I saw it in 1827. 



X Quart. Journ. Geol. Soc. vol. vii. p. 50. 



