844 DE B. N, PEACH AND DE J, HOENE ON 



sandstone and Birrenswark volcanic zone near the junction of the Liddel and Hermitage 

 Water. (See Plate III. section 1.) 



In Upper Liddisdale, to the east of the Silurian inlier just referred to, near Kiccarton, 

 the Cementstone group is again repeated, resting in natural sequence on the Whita 

 sandstone and Birrenswark volcanic zone, and dipping towards the south-east. In that 

 district they floor the course of the Liddel Water, and form the lower slopes of the 

 Larriston Fells. Owing to minute folding of the beds it is difficult to give an accurate 

 estimate of their thickness, but it is probably about 1200 feet. The Larriston Burn 

 furnishes a good section, especially of the marine limestone zone, near the top. 



iv. The Fell Sandstones. 



The Cementstone group of Liddisdale and Eskdale is overlaid by a succession of 

 sandstones, with intercalations of red and green marly clays, and occasional impure 

 cementstone bands, varying in thickness from 400 to 600 feet. The sandstones are 

 siliceous and usually fine-grained, but sometimes become coarse and pebbly. At certain 

 localities they contain marine fossils such as Aviculopecten, while the impure limestone 

 bands contain cyprids and modioliform shells, but there is no indication of clear water 

 conditions. 



In the district of Peel Fell there is evidence of successive land surfaces in the form 

 of dirt beds, and even of thin coal-seams, which accompany the red and green marls and 

 impure fireclays separating the beds of sandstone. 



From a stratigraphical point of view this group of sandstones is of great importance, 

 inasmuch as the zone is persistent and easily traceable. They form much of the 

 higher part of the Larriston Fells, where they lie in a synclinal fold, overlaid by the 

 upper volcanic zone at the base of the Lewisburn coal-bearing beds (Scremerston 

 position), to which reference will be made in the sequel. (See Plate III. section 1.) 

 When traced towards the south-west, owing to the fall in the ground, the Fell sandstones 

 appear in the centre of the trough, but on Caerby Hill they are capped by the upper 

 volcanic zone. Crossing the Liddel at Kershopefoot, they extend westwards along the 

 slopes south of the Tinnis Burn, and form the high ground separating that stream from 

 the Tarras Water. They are visible in the Esk at Irvine House, and towards the 

 south-west they are traceable across the moorland to the south of Ecclefechan, where 

 they form the prominent eminences of Brown Moor and Woodcock Air, on either side 

 of the Annan. West of the Nith this zone appears on the shore between Arbigland and 

 Southerness Point. 



v. Glencartholm Volcanic Group. 



Next in order above the Fell sandstones comes the volcanic group of Glencartholm, 

 which, though of no great thickness, has been of service in working out the strati- 

 graphical arrangement of the beds between the Esk and the Liddel. In the Esk section 



