1850.] STEVENSON ON O. R. S. CONGLOMERATE. 421 



Between East and West Aikengalls is a deep and wide hollow, with a 

 marshy bottom, but without any stream running through it. This 

 runs in a W.N.W. direction, and has evidently had a similar origin. 

 The conglomerate, both on the East Lothian and Berwickshire 

 sides of the Lammermuirs, is separated from the upper members of 

 the old red sandstone and the lower beds of the carboniferous system 

 by a series of dislocations of great complexity, and many of them of 

 very great extent. These appear all to run in certain determinate 

 directions, or at least as near to such as the nature of the strata with 

 regard to the degree of resistance opposed, would admit. These 

 directions are N.N.E. (or parallel to the strike of the greywacke in 

 this part of the Lammermuirs), W.N.W. (or at right angles to the 

 said strike, being also the direction of the claystone dykes and fissures 

 before mentioned), N.N. Wand E.N.E. (theselastheing intermediate 

 to the former directions). 



Of these dislocations the most remarkable is that which extends 

 from a point near the Knock Hill (about two miles from Dunse) in a 

 direction nearly S.S.W., passing along the east side of the conglome- 

 rate hills of Hardens, and proceeding by way of Choicelee, March- 

 mont, &c., crossing the Tweed near the mouth of the Teviot, and 

 traversing Roxburghshire by way of Hunthill, Southdean, the upper 

 part of the Jedwater, the east side of Lariston Fells, &c. The 

 strata all along this line of fault are thrown down on the east side. 

 The amount of displacement along the east side of the Hardens is 

 probably at least 500 or 600 feet. Near Choicelee the old red sand- 

 stone strata adjoining the line of fault are retrojlexed for some distance. 

 A very interesting circumstance may here be mentioned. This is the 

 occurrence in Roxburghshire of a gap in the greywacke precisely 

 similar to that which forms the subject of the present notice. This 

 gap is filled up by strata of the old red sandstone and lower carbonife- 

 rous formations, and runs parallel with the line of dislocation referred 

 to. Its situation is also exactly the same with regard to the disloca- 

 tion as the Lammermuir gap, both occurring about three miles to the 

 westward of the course of the fault*. The width of the two gaps is 

 also very nearly the same. In fact that part of the county of Rox- 

 burgh which lies to westward of this line of fault is almost the counter- 

 part, in its geological features, of the corresponding portion of Berwick- 

 shire. The Hawick trap dyke intersects this line of fault near Fall- 

 side, in Chesters parish. 



Besides this, there are several other dislocations connected with 

 the conglomerate. One runs E.S.E. from Elmford for a few miles, 

 throwing down the strata on the south side. Another proceeds 

 S.S.E. from Elmford to the east side of the Knock Hill, where it 

 meets the great dislocation first described. It throws down on the 

 east side to the extent, in some parts, of probably 800 feet. On the 

 Lothian side of the Lammermuirs, in the prolongation of this line, is 

 a similar dislocation, which passes near Halls, and also throws down 

 on the east side. A fault running nearly at right angles to this (E.N.E.) 



* See map attached to Mr. Milne's paper on the Geology of Roxburghshire. 



