TRANSACTIONS OF THE SECTIONS. 93 



On ilie Silurian liocl'S of the SoutJi of Scotland. By D. J. Bro-wn. 



This paper was illustrated by a map and section, also specimens of rocks and 

 fossils. 



In a section drawn from Moffat Water in Dumfriesshire to Kilbucho in Peeble- 

 shire, we have, first, the Bloffat rocks, which consist of hard blue grit {Grey- 

 wacke) and shale. These are accompanied by beds of anthracite and black shale 

 containing Graptolites ; on leaving IMoffat Water, we first meet anthracite beds, 

 then a series of grit and shale ; this order is repeated six times. The last time we 

 see anthracite beds is at Holmes-water-head, where we find them plunging under 

 the limestone and conglomerate of Wrae and Glencotho, over the whole length 

 of the section from Motfat Water to Holmes Water. The beds stand at a high 

 angle, and have an almost uniform northernly dip. From Holmes Water to Kil- 

 bucho the rocks are of a more diversified character. We have first a coarse angular 

 conglomerate, then a bed of limestone with fossils, mostly of a Caradoc type ; next 

 a series of beds of slate, shale, and grit ; these beds come up again at Kilbucho. 

 After Holmes Water we have no longer the imiform northernly dip, but the beds 

 undidate, and in one section are seen to form regular waves. 



These beds all along the line of the section, from the river Tweed to Kilbucho, 

 are given in the Government Geological Map of Peebleshire as one series of Llan- 

 deilo age. The author is of opinion that they form two series — a lower Mofiat or 

 Llandeilo, and an upper or Caradoc series that lies imconfomiable upon the lower. 



The author has come to the conclusion that the two series are imconformable : — 

 First,because we find the anthracite beds at a high angle plunging under the limestone 

 and Conglomerate of Glencotho and Wrae at Holmes-water-head, and emerging at 

 the same angle in the Moor-foot Hills. Second, because we find these upper rocks 

 everj-where underlaid by a bed of coarse angular Conglomerate; and this conglomerate 

 is found in fragments, and nowhere in situ, in the neighbourhood of Moffat, which 

 is on the opposite watershed, being, as the author thinks, fragments of the lower 

 rocks left in the process of denudation. Third, this Conglomerate is found to con- 

 tain numerous fragments of anthracitic shale containing Graptolites belonging to 

 lower beds, proving that the lower rocks were consolidated, and then torn into frag- 

 ments before the upper rocks were laid down. 



On the Upper Silurian liocls of the Pentland Hills and Lesmahago. 



By D. J. Brown. 



This paper was illustrated by a map and two sections. 



In a paper published in the Transactions of the Edinburgh Geological Society, 

 vol. i., written by Mr. Henderson and the author, it was shown that in the North Esk 

 section of the Pentland Hills there is a very perfect Wenlock fauna, and that it is 

 only towards the top of the section that the Ludlow species come in ; it was further 

 shown, from Silurian fossils collected from the Red Conglomerate lying at the 

 top of the section, that these Red Conglomerates were not a part of the Lower 

 Old Red Sandstone, but a continuation of the Silurian, and that the whole Silurian 

 rocks in the Lyne water form a continuous section above them. In the district 

 of Lesmahago the Upper Silurians are said to form a continuous series with the 

 Lower Old Red Sandstone that lies above them. In " Memoir 32, Geological Sur- 

 vey of Scotland," the same phenomena are said to occur in the Pentlauds, and Mr. 

 Salter draws a parallel between these beds and those of Lesmahago ; but from this 

 comparison he omits the section in the Lyne water, which forms a continuous series 

 above the Red Rocks, said to be Old Red Sandstone, so that these Old Red Sand- 

 stone beds of the Government Survey lie ri^ht in the centre of the continuous sec- 

 tion of Upper Silurian, and contain Upper Silurian fossils. As it is only towards 

 the top of the North Esk section that we find any fossils belonging to the Lesma- 

 hago beds, and they difler from them very much in their hthological character, the 

 author is of opinion that these beds are not the equivalent of the Lesmahago beds 

 but that these latter form an upper series overlying the Pentland beds. 



