364 Mr. George Tate on the Cheviots. 



western flanks of the Cheviots in Roxburghshire ; at Bloody- 

 laws on the Oxnam they are seen dipping northward sixty 

 degrees, and at Rink southward about seventy-five degrees ; 

 but they are generally nearly vertical with a pretty uniform 

 strike from west-south-west to east-north-east. 



The precise correlation of these greywacke beds is not yet 

 ascertained ; but this much is certain ; they are much older 

 than the old red sandstone conglomerates which cover them 

 unconformdbly in Berwickshire and Roxburghshire. Fossils 

 have not been detected in them in Northumberland ; but 

 Mr. Wm. Stevenson, of Dunse, found a graptolite and tracks 

 of an annelid in greywacke on the Dye water, but in beds 

 apparently high up in the system. Probably these strata 

 are about the same age as the Longmynd rocks referred by 

 Sedgwick to the Cambrian and by Murchison to the lower 

 Silurian system; and hence until more definite evidence 

 is obtained, they may conveniently be designated Cambro- 

 Silurian, 



2. Red .Sandstone Conglomerates of considerable thickness, 

 but occupying an inconsiderable area, appear on the flanks 

 of the Cheviots at Roddam and Biddlestone in Northumber- 

 land, at elevations from 500 to 700 feet above the sea level. 

 In the deep, narrow dene of Roddam they are exposed up- 

 wards of a mile, consisting principally of conglomerates, 

 formed of rounded pebbles of Cheviot porphyry^ from the 

 size of a pea to that of the human head, scattered through a 

 flesh and brick red clay and sand, loosely bound together by 

 peroxide of iron. Interstratified with these are thin beds ot 

 harder conglomerate with smaller pebbles, and thin beds of 

 greenish chloritic, calciferous sandstones, some of which con- 

 tain as much as 40 per cent of carbonate of lime. Above the 

 loose conglomerates are soft, thin, bedded red sandstones, and 

 below them are hard red sandstones with large ripple marks. 

 These beds are not less than 500 feet thick, dipping gener- 

 ally E.S.E. 15 degrees,but, occasionally, as much as 50 degrees. 

 Organic remains I have not found in them ; but, as their 

 mineral characters and geological position correspond with the 

 old red conglomerates of Berwickshire and Roxburghshire, 

 theymay, without much doubt, be grouped with that formation. 

 In Biddlestone burn they are close upon the porphyry of the 

 Cheviots, sloping away from it to S.S.E. at an angle of 25 

 degrees, and are there overlaid conformably by Tuedian 

 strata. 



The red conglomerates of the Border counties are more 



