Mr. George Tate on the Cheviots. S65 



connected with the carboniferous than with the Devonian 

 system. Their relations are best seen in the section from 

 Siccar point to the northern extremity of Berwickshire, 

 where they distinctly rest on the upturned edges of the 

 greywacke or Cambro-Silurian strata ; and are conformably 

 overlaid by beds of the Tuedian age, the line between the 

 two being marked by the occurrence of Holoptychius Nohil- 

 issimus in the red conglomerate, and of Stigmaria Jlcoides in 

 the Tuedian beds. In this upper old red sandstone one de- 

 terminable plant, Adianthoides Hihernicus, has been found in 

 Berwickshire ; and from similar beds in Roxburghshire, I 

 have seen casts of pretty large stems, probably belonging to 

 a sigillaria. Mr. D. Milne Home notices that sandstone 

 within twenty yards of the Cheviot porphyry on Jed water 

 contains rounded pebbles of Cheviot porphyry.* 



3. Strata of the Tuedian formation, which is intercalated 

 between the upper old red sandstone and the mountain lime^ 

 stone, were, by a great flood, exposed in Akeld burn, in 

 direct contact with the syenite of the Cheviots. The section 

 there is of considerable interest, and shows a calciferous, soft- 

 ish sandstone of a pale greenish hue specked with yellow, 

 lying against the syenite, but dipping away from it N. by E. 

 85 degrees ; and this is followed by about 100 feet more of 

 greenish and grey shales, interstratified with thin beds of 

 cherty limestones, which weather buff, and a few beddy 

 micaceous sandstones. These strata are similar to the Tuedian 

 rocks in the Tweed and Whiteadder ; in the shales are re- 

 mains of fish, and scales oi Rhizodus Hihberti, reed-like stems 

 to which is attached Spirorbis carboiiarius , Stigmaria jlcoides , 

 and a species of Sphenopteris. The section evidences not 

 only the upheaval of the stratified rock, but also considerable 

 mechanical disturbance ; the slope throughout is nearly per- 

 pendicular, but in one part, which is obscured, there is a 

 fault by which the dip is reversed. 



Sandstones of the same formation, in detached blocks, can 

 be traced on Whitelaw — the hill east of Yevering — as high 

 up its slope as 900 feet above the sea level, while the same 

 rock in mass mantles the hills at a level of about 500 feet. 



In other parts of the range, rocks of the same formation 

 appear. In Biddlestone burn they overlie conformably the old 

 red conglomerates ; but more extensive sections of them are 

 seen in the Ridlees burn, and, on the Coquet from Linn brig to 

 Alwinton, where about 1000 feet of characteristic sandstones, 



* Geology of Roxburghshire. • 



