Formation and Age of the Queensberrys. 249 



accurate solution of the perplexities of the strata, and also fur- 

 nished a means of co-relating these deposits to their equivalents 

 elsewhere. In 1878 his famous paper on "The Moffat Series " 

 appeared. It was at once admitted to be " the greatest contribu- 

 tion to the study of these highly convoluted rocks." Since then 

 the survey officers have re-examined the ground and confirmed and 

 extended the discoveries of Professor Lap worth. The result of 

 their work is now published in the monograph, " Silurian Rocks 

 of Scotland." So far as the Queensberrys are concerned, these 

 conclusions may be stated briefly. Near the bottom of a great 

 mass of greywacke there is a group of black shales about 300 feet 

 thick. They consist of three parallel bands, representing three 

 distinct ages. The bands are sub-divided into different zones, 

 each of which is characterised by a different type of fossil. 

 The principal fossils are of the Graptolite family peculiar to the 

 deep seas of that period. During the earliest ages the various 

 species were of the simplest character, consisting of few organs. 

 From that primitive type to the final disappearance of the race 

 there was a continual evolution in their structure and habits. A 

 comprehensive study of the successive developments evolved in 

 the Graptolites gave Lapworth the key to unravel the complica- 

 tions of stratigraphy, and to establish a definite and continuous 

 order of rock formation throughout the ages of the Silurian epoch. 

 In order to realise the difficulties of field work, and also grasp its 

 real significance, we must examine the rocks themselves. Two 

 sections will be sufficient — the Glenkiln Burn, exhibiting the 

 lower formations, and the Pishnack Burn, completing the record 

 with younger strata. 



In the Glenkiln Burn, about 1^ miles above its confluence 

 with the JE, a great mass of black shale is laid bare bv the stream. 

 At the point where the Glenkiln is joined by the small triUutary 

 (Lambfoot Burn) a deep, narrow gorge has been cut through the 

 softer shales, exposing one of the finest rock sections in the south 

 of Scotland. At the tributary's mouth, on the right bank, there 

 is a fine display of hard shattery shales. A hundred vards fur- 

 ther up stream on the opposite bank they form a prominent escarp- 

 ment of black rock. They are technically known as the Glenkiln 

 Shales, and are associated with bands of radiolarian chert and 

 volcanic lava. Although these shales are richly charged with 

 graptolites, yet good specimens are difficult to obtain owing to 



