﻿1850.] HARKNESS ON THE SILURIANS OF DUMFRIESSHIRE. 49 



this neighbourhood. My attention was directed to this dike by Sir 

 Roderick Murchison, who, seeing that its course to the S.E. passed 

 by Craig Fell Hill, thought it would probably be found to proceed 

 from the great mass of trap near Langholme. 



At Duff Kinnell, not far from Rae Hills, and at several other spots 

 in the neighbourhood, the same anthracite and shales are found. 

 One species of Graptolite (G. Sedgwickii) occurs here in great 

 abundance and of large size ; other species also are found, but not in 

 such great numbers. The dip in this locality is more to the westward 

 than commonly prevails, being at an angle of 50° W.N.W., and 

 consequently the strike of the beds between this and Beatock has a 

 more north and south direction. In the bed of the river Kinnell 

 the same direction of dip prevails amongst the purple and grey wacke 

 sandstones which are there exposed. 



In the Glenkiln Burn, in the parish of Kirkmichael, about eight 

 miles north from Dumfries, we also find these graptolitic beds. In 

 the lower portion of the brook, and below where the anthracite occurs, 

 fine-grained grey wacke sandstone is met with, dipping N.N.W. at 

 an angle of 55°, the beds varying in thickness, and interstratified with 

 red and purple shales. Higher up the brook, beds of a similar na- 

 ture are seen, but the inclination is only 30°. Above these the dip 

 again becomes 55° ; and here are seen hard shaly anthracite beds, 

 including softer shales, and resting apparently immediately upon the 

 grey wacke sandstone. In these deposits Graptolites are occasionally 

 seen, including G. Nicoli. 



In some portions of the anthracitic shales, small nests of a black 

 carbonaceous matter resembling soot are frequent. These strata are 

 much contorted, and traversed by thin veins of white quartz ; they also 

 present the slickenside appearance so common to this deposit. Im- 

 mediately above the anthracite a shivery greywacke is seen, imper- 

 fect in its stratification ; succeeding this are regular stratified beds 

 similar to those which occur lower down the brook, dipping at an 

 angle of 40° N.N.W. ; above these lies a dark, shivery, slickensided 

 shale, not anthracitic, in which Graptolites occur in great quantities. 

 Above this shale a bed of greywacke, similar to that which overlies 

 the anthracite, is met with. This is succeeded by regularly bedded 

 strata, similar to those in the lower parts of the brook-course, and 

 having an inclination towards N.N.W. at an angle of 45°. Above 

 these, thin beds of greywacke, with interstratified, soft, purple shales, 

 variegated with a greenish grey colour, are found, dipping N.N.W. 

 at an angle of 37°. 



The stratified deposits along the course of this brook afford a good 

 example of the general character of the rocks which make up 

 the Silurians of Dumfriesshire. But the sequence of the deposits 

 cannot here be made out, as several faults intersect the strata and 

 entirely destroy all traces of conformity. For instance, in the lower 

 portion of the burn we have the anthracite without its overlying dark 

 shales ; and higher up we find the dark shales without the under- 

 lying anthracite. The shivery character of some of the greywacke 

 strata indicates the position of the lines of fault. 



VOL. VII -PART I. E 



