460 Lapivorth & Wilson— Silurian Bocks of Roxburgh & Selkirk. 



One goes very near to the great fault from the north slope of the 

 Moorfoots to the Gala near Heriot Station ; the second, from the 

 centre of Blackhope Bum, down the lower course of the Heriot 

 water ; while a third cuts through the high ground at the sources of 

 the Leithen and South Esk. These beds are much altered and 

 crushed, but we have obtained a great number of Moffat Graptolites 

 from each and all of them, more especially from Browbeat Eig, 

 where the fossils are most numerous and in the best preservation. 



From the northern line we obtained : — 

 Diplograpsiis pristis, Hia. Diplograpsus vesimlosus, and a Bicranograpsus. 



Climamgraps'us teretiusculus, His. 



From the middle band : — 

 Diplograpsus pristis. His. Diplograpsus tamariscus, 



„ vesimlosus, Nich. Cladograpsus linearis, Carr., etc. 



While the third line has yielded in addition : — 

 Dicanograptus ramosus, Hall. Dicellograpsus Morrisii. 



Dicellograpsus „ sp. „ Moffatensis, Carr. 



and a few others. 



The Gala Group. — Lying in the irregular trough formed by these 

 two appearances of the Moffat rocks, we find an entirely distinct 

 series of strata of a very varied lithological character, and known to 

 us as the Gala group. We made out enough of the fossils of these 

 beds in 1869, to see that they formed a fauna clearly separate and 

 distinct from that of Moffat, and our discovery was published in a 

 paper read before the Geological Society of Edinburgh, in March, 

 1870.^ At that time, our investigations had been confined to the 

 beds in the neighbourhood of Galashiels, but we have since examined 

 a great deal of the country, both to the west and north, still finding 

 the same fossils. In that paper, we split up the beds as known to 

 us into four portions, which were, however, almost entirely geogra- 

 phical, and were only useful as an index of the localities of the 

 different fossil forms. Although we have expended a great amount 

 of labour on the group since that time, we think that it would be 

 rash were we to attempt to give any sub-divisions at present, though, 

 with such well-marked differences in the strata, we are of opinion 

 that it will soon be possible to split up the formation. 



The usual type of rock is a grey thick-bedded grit, separated by a 

 seam or bed of shivery shale, but there are large areas of purple 

 sandstones and mud-stones, and thick beds of grey shale, together 

 with masses of pebbly grit and conglomerate. 



One of the lines of pebbly grit runs for a mile or two close to the 

 north of the town of Galashiels, while a second appears to underlie 

 the Grieston Slates from the head of the Douglas Burn almost to 

 the town of Stow, a distance of fourteen miles. It consists in its 

 typical form of a coarse grey grit, containing large nests or heaps of 

 pebbles, rounded and angular, that often weather out, and leave a 

 honeycombed rock of a peculiar appearance. It is seen, however, 

 in some places entirely without these pebble-beds, and bears only a 

 large solitary stone here and there. 



1 See Geol. Mag., 1870, Yol. Til., p. 204, PI. Till., and p. 279. 



