458 Lapworth 8f Wilson — Silurian Rocks of Roxburgh d Selkirk. 



as they occur in this way, first to the north, then to the south, of this 

 axis : — 



1. The Hawick Bocks. — The great anticlinal and the beds for a few 

 miles on either side consist in this district of very arenaceous grey 

 and purple sandstones and schists. The purple colour is most con- 

 spicuous in the west between Dumfries and the dreary uplands of 

 Eskdale-muir, but dies almost entirely to the east, where we find the 

 prevailing tint is a dull brownish grey. These strata are best seen 

 on the hills to the north of the town of Hawick, where their up- 

 turned edges, which are singularly bare of soil or clay, have been 

 cut and carved by the old ice-sheet into narrow streamless valleys, 

 sometimes closed at one end by an abrupt cliff of rock overhanging 

 a lonely tarn. 



Professor Harkness found the track of a Crustacean in these beds 

 at Binks, a few miles to the south of the axis. We have ourselves 

 detected Protovirgularia and Annelides within a mile of it ; but our 

 friend Professor Elliot of Goldielands, who has devoted himself to 

 the careful investigation of these strata, has met with much greater 

 success, and has procured specimens of worm-tracks, Arenicolites, 

 Protichnites trichoides, rain prints, ripple markings, and those 

 peculiar forms called plants by some of the American geologists, in 

 great variety and abundance. 



These ancient rocks bear a strong resemblance both in their litho- 

 logical characters and in their fossil contents to the Cambrians of the 

 Longmynd, but they are very probably of later age. 



2. The Selkirk Beds. — As we proceed farther from the axial line, 

 the arenaceous character of the rocks is gradually lost, and we pass 

 insensibly upward into a great thickness of fine grained grits, flags, 

 and shales of a very light grey or greenish colour. The whole of 

 the beds are much crumpled and jointed. The thicker strata are 

 usually veined with calc-spar, some of the veins being more than a 

 foot in thickness. Almost every joint is coated with the same sub- 

 stance, and this gives the whole set of strata a very peculiar ap- 

 pearance. These rocks cover a large tract of country to the west of 

 the Hawick rocks, which, however, gradually decrease as we proceed 

 to the south-west, where we have found that the Selkirk and Hawick 

 beds slowly die away to a point between the Upper Silurian and 

 Moffat beds of Kirkcudbright. 



We have only procured a couple of species of Protovirgularia, a 

 Crustacean, and a few Annelides from these rocks ; but the beds look 

 very promising in places, and we expect a much richer harvest in the 

 future. 



3. The Moffat series. — Immediately to the north of the Selkirk beds, 

 we reach another set of strata of a little more inviting appearance. 

 It consists of thick and thin beds of greywackes and shales of a dark 

 grey or greenish colour, often weathering, especially where a little 

 altered, of a brownish or yellowish colour. The great feature of the 

 series, however, is the bed of anthracitic shale at its summit. This 

 band is of incalculable assistance to us in working out the order of 

 this portion of the system, as it seems to be continuous from sea to 



