444 MR MILNE ON THE GEOLOGY OF ROXBURGHSHIRE. 



on the same strike or outcrop, which in like manner contains galena. It is pro- 

 bably a prolongation of this bed still farther westward which, near Alstone 

 Moor, affords so large a supply of lead. The other fact is, that the same vermi- 

 cular looking fossils, indicating an animal two or three feet in length, found 

 in the slaty sandstones of Halt whistle,* have been found by me in a sandstone 

 rock of precisely the same character, on the sea-coast at Scremerston, between 

 Holy Island and Berwick. 



Some more special notice is deserving of the limestones found in the class of 

 rocks now under consideration. There are three kinds, viz., carbonate of lime or 

 ordinary lime-rock, Chert limestone, and magnesian limestone. 



(1.) The first kind is that worked at Meadow-cleugh on the Carter, at Lime- 

 kiln Edge, between Hawick and Castleton, at Lariston, at Harelaw Hill, and at 

 Gilnockie Tower on the Esk. 



At Harelaw Hill the rock is about 14 feet thick. It is compact, and of a bluish 

 colour. There are, however, several other beds of limestone, one of which is said 

 to be above 20 feet thick. 



At Lariston the rock is of a bluish-grey colour, and several yards in thickness, 

 divided, however, by one or two beds of shale or fire-clay. It abounds with marine 

 shells, such as the productus and the modiola, which last shell I have also seen 

 in the old Greenholm quarry. This bed of limestone is thought to lie above the 

 Carter limestone. 



The limestone at the places just mentioned, and most of the others where it 

 is worked, contains numerous casts of the productus, orthoceras, encrinites, and 

 other marine mottusca. The quarries at Limekiln Edge and the Carter are, how- 

 ever, exceptions to this remark, which may perhaps be owing to changes produced 

 on their texture by large masses of trap-rocks adjoining them, to be afterwards 

 described. 



At Limekiln Edge, the bed worked is about 12 feet thick. It presents some 

 remarkable undulations, which have nothing to correspond with them in the strata 

 above or below. These undulations are seen also in the Berwick coal-field ; and 

 I understand from Lord Greenock, that he has seen them near Cambo in North- 

 umberland, about twenty miles south of Cheviot, through which district the same 

 limestone beds undoubtedly run. The occurrence of these undulations between 

 horizontal beds have not, I believe, been explained, and I confess my inability to 

 offer any plausible hypothesis. 



* Geological Society's Transactions. 



