MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



445 



Section from Limestone quarry at Limekiln Edge. Depth 20 feet, length QQfeet. 



A A, Stratum of gravel. 



B B, Blue marly clay in horizontal layers, containing undulatory strata of limestone. 



C C, Limestone 4 feet thick. 



DD, Limestone 6i feet thick. 



f 



The only analysis of this class of limestones which I have obtained, is of that 

 worked at the Carter, made by the present Professor Gregory of Aberdeen. The 

 following shews the constituent elements of three specimens : 



Carbonate of lime 



Magnesia, 



Insoluble matter (sand), 



80 

 3 



17 



100 



90 90 



trace. 5 



7 5 



97* 



100 



(2.) The chert limestone occurs at Robert's Linn (on west side of Windburgh), 

 Windshielknow, Kerchester, Bedrule, Smailholm, and Sprouston. 



At all these places, the rock is accompanied by sandstones, marls, and shales, 

 which appear to me to belong to the coal-measures. 



The rock has not much lime in it, though at Hadden and at Bedrule it has 

 been quarried and burnt for agricultural purposes. It is highly crystalline, con- 

 taining large nodules of quartz or chalcedony, generally coloured red. On an 

 analysis of the Hadden limestone, there was found to be (out of 100 parts) 50 



It is observed by Mr Gregory, " that this slight deficiency is probably owing to a little water, 

 which most limestones contain." 



VOL. XV. PART II. 



6E 



