C. Lapworth. — Geology of Galashiels. 279 



VII. — On the Lower Silurian Eooks of Galashiels. 



By Charles Lapworth, Esq, 



{^Continued from the May Number, p. 209. ^ ) 



(B.) The Gala Group, continued: — 



(3.) The BucJcholm Sandstones. — These beds are characterized by 

 the evidence they afford of having accumulated in shallow water. 

 They consist generally of gritty greywackes and light green or red, 

 sandy, incoherent shales and mudstones. 



The greywackes are usually schistose or thick -bedded, of purple 

 or blue colours, and contain, much mica ; while the shales are 

 exceedingly arenaceous, and are replaced at times by beds of mud- 

 stone or finely-levigated mud-shale, covered with the trails of 

 Annelides, or spotted with little discolorations, due to the former 

 presence of organic matter ; while the whole set of strata is marked 

 by its arenaceous and generally incoherent character, and the warm- 

 coloured or rusty appearance of the rocks, so different from the cold, 

 hard, forbidding aspect of the inferior strata. Yet, in spite of these 

 more inviting characteristics, there are not many fossiliferous spots, 

 though they are far more common than in the beds below. These 

 beds are well exposed along the flanks of Buckholme and Meigle to 

 Caddonfoot, and thence in the railway cuttings to Thornilee, and 

 are recognizable at once by their peculiar character and the narrow 

 bands of white or bright-coloured shale seen here and there among 

 the dingier strata. 



These beds, as might have been expected, are by far the most 

 varied in their organic remains, and contain GraptoUtes priodon, G. 

 SedgwicMi, principally proteus, G. colonus (Barr), G. turriculatus 

 (Barr), G. exiguus (Nich.), which is found in myriads in some of the 

 beds, Betiolites perlatus (Nich.), and Bastrites Linncei (Barr), together 

 with some small forms of Diplograpsus as yet undetermined ; Crosso- 

 podia Scotica (M'Coy), Nereites Cambrensis (Murch.), Nemertites 

 tenuis (M'Coy), Trichoides ambiguus (Hark.), Protichnites sp., Proto- 

 virgularia Harhnessi, traces of the swimming paddles of Crustacea, 

 Pterygotus? sp., Ceratiocaris (three species), Tentacidites sp., Discino- 

 caris Browniana (Wood), Fenestella, together with many that are as 

 yet indeterminable. 



(4.) Slates of Thornilee and the Grieston. — I have placed these 

 together because of their general similarity lithologically, both 

 consisting of fine-grained shales, splitting into thin layers along the 

 original lines of bedding, and from the circumstance that they both 

 appear to be underlaid by the Buckholm beds or their representatives, 

 and also from the fact that ihej both contain a fauna which most 

 nearly approaches that of our higher beds. But I am compelled to 

 admit that they may be two distinct deposits, separated by an 

 enormous interval of time. In fact, much of the evidence points in 



1 The Map of the District described in this paper accompanied the first part, and 

 will be found in the May Number (Plate VIII).— N.B. In the Scale, of the Map 

 for " 2 miles to 2 inches," read " 2 miles to 1 inch." 



