Mr. WiTHAM on the Red Sandstones of Berwickshire. 181 



ton-mill, below the Red Sandstone, and conformable to it), are found 

 numbers of stems of Gymnospermous Phanerogamous Plants, also Sigil- 

 larite, Lepidodendrce, and leaves of Ferns. This locality is about seven 

 miles from Lennel-braes, where plants belonging to the same class 

 are to be found in great abundance. 



There, therefore, appears no doubt, that were the Shales of this dis- 

 trict properly examined, many of these ancient vegetable fossils might 

 be found. This, I trust, will encourage gentlemen living in the neigh- 

 bourhood of other Mountain Limestone groups, to examine attentively 

 these apparently fruitful deposits. Many of the fossils occurring here, 

 as well as at Lennel-braes, are partly mineralized with Iron Pyrites. 

 This substance appears to decompose, upon exposure to the atmosphere, 

 and the sulphuric acid uniting with Lime produces beautiful crystals 

 of Selenite, which are found in abundance at both places. 



Three miles above Coldstream, at a place called Hindley-top, are to be 

 found many thin alternating beds of Shale and Blue Limestone. In 

 one of these Shale beds. Gypsum occurs. The fibrous variety, in layers 

 about half an inch thick, and the common, in nodules of a flesh red 

 colour, having beautiful crystals of Selenite in them. 



In order to ascertain the position of the rocks on the south side of 

 the river Tweed, twelve miles from the coast, and with reference to 

 those on the north of that river, I proceeded up the bed of the river 

 Till, where I found the rocks rising to the N. N. W. at an angle of 

 about 8° until I came within the bounds of the eruptive force of the 

 Cheviots, when they appear to rise to the west. This alteration of 

 dip, caused by the proximity of Transition rocks, I also found to be the 

 case generally at the base of the Lammer-muir hills. 



In proceeding up this river, a short way above Heaton-mill, I ob- 

 served a singularly beautiful Basaltic Dyke, containing much Chloro- 

 phaeite. This Dyke runs from east to west, and I have the satisfaction to 

 say it has been traced by my friend Mr. Milnes, of Milgraden, from a 

 short way below Coldstream, where it appears on the south side of the 

 Tweed, opposite to Lennel House. Here it is from 8 to 10 feet wide. 

 It then runs directly east to Milkington, where it increases in breadth to 



VOL. I. B b 



