866 



DR B. N. PEACH AND DR J. HORNE ON 



3. Elves Water by Archerbeck to the Liddel Water. — On the north-west slope of 

 Whita Hill, east of Langholm, the unconforrnability at the base of the Upper Old Red 

 Sandstone is well seen, as shown in section ; the members of this formation being 

 followed by the Birrenswark volcanic zone and the Whita sandstone. South-eastwards, 

 towards the Tarras Water, the Cementstone group succeeds, excellent exposures of which 

 are visible in the latter stream, overlaid in turn by the Fell sandstones (d lv ), the basic 

 tuffs of the Glencartholm volcanic zone (d v ), and the beds on the horizon of the Law- 

 ston coals (d vl ). By means of a north and south fault on the moor between Tarras 

 Water and Archerbeck, the two last groups are repeated as shown in section 3, followed 

 by higher beds of the Marine Limestone series which stretch across the moorland to 

 Archerbeck. In the latter stream, at a point about two miles above its junction with 

 the Liddel, the arch of Lower Marine Limestones (d vii ) is truncated by a fault with a 

 downthrow to the south (see section). On Harelaw Hill the massive Lower Marine 

 Limestones again appear from underneath the beds on the horizon of the Kilnholm coals 

 (Lickar position), and to the south-east at Pen ton Linns in the Liddel, as shown in section, 

 the same limestones are exposed in sharp folds, being followed on the English side of 

 the border by the thin Kilnholm coals, which are cut off by the great fault that throws 

 down the red sandstones of the Upper Coal-measures (d xili ). 



4. Wauchope Water by Glencartholm, Byre Burn, and Rowanburn to the Liddel 

 Water. — This section has been prepared to show the relations of the strata in the Esk 

 below Langholm and in the Rowanburn coalfield, as proved by the mining plans. It is 

 observable that the sequence from Langholm to Glencartholm is extremely clear, each 

 group, from the Whita sandstone to the Glencartholm volcanic zone, with its fossiliferous 

 shale, following each other in natural sequence. Between Glencartholm and the foot of 

 Byre Burn the various subdivisions of the Marine Limestone series are met with, which 

 are affected by numerous small faults and folds, most of which are omitted in the 

 section. The small patch of Middle Coal-measures at Byre Burn is represented (d xn ), 

 bounded on both sides by faults ; but without the assistance of the fossil plants, the 

 field geologist would hardly realise from the evidence on the ground that the Middle 

 Coal-measures are there faulted, on the north-west side, against the higher part of the 

 Marine Limestone series. The section further shows the gently inclined and faulted 

 coal-seams of Rowanburn curving upwards, along the south-east margin near that 

 colliery. 



The remaining portion of this section is of special interest, as it shows the position 

 of the great fault that bounds the Rowanburn coalfield on the south, the belt of 

 Carboniferous red sandstone of the Upper Coal-measures (d xiii ) beyond, overlaid uncon- 

 formably by the Triassic sandstones to the south. 



5. Birrenswark by Ecclefechan to the Kirtle Water. — This line of section lies about 

 twelve miles to the west of the river Esk, and furnishes important evidence of the great 

 unconforrnability at the base of the Trias in that part of Dumfriesshire. From the 

 slopes of Birrenswark the basic lavas dip gently southwards, followed by the Whita 



