GEOLOGY OF DUMFRIESSHIRE. XXXV. 



carboniferous limestone in these breccias in the basin of the Annan, 

 south of Lochmaben. Recently, when cutting the road to the hydro- 

 pathic establishment at Moffat, nodules of impure limestone were found 

 in the breccia. From these nodules the following fossils were obtained : 

 Natichopsis plicistria, Camerophoria crumena and Bellerophon, belong- 

 ing to the cementstone series. It is clear, therefore, that patches of 

 carboniferous strata must have existed in these valleys during the 

 deposition of these breccias. In the red sandstones of Corncockle Moor 

 and to the south of Dumfries, reptilian footprints have been detected. 

 The breccias have probably accumulated in narrow fjords, and the red 

 sandstones may have been deposited in enclosed basins. The strata 

 are singularly destitute of organic remains, and though at present they 

 are provisionally regarded as Permian, it is not improbable that they 

 may be of younger date. An interesting feature connected with the 

 Thornhill basin is the occurrence of contemporaneous volcanic rocks 

 at the base of the Permian beds. They form a prominent belt, usually 

 rising to the surface as a distinct ridge, between and underlying carboni- 

 ferous strata and the over-lying Permian rocks. They consist of slaggy 

 diabase lavas and tuffs, which are occasionally interstratified with the 

 sandstones. 



Beyond the limits of the Thornhill basin there is further evidence 

 of the extension of these volcanic rocks at Lockerben, about ten miles 

 to the east of Thornhill. Here there is a small isolated area of carboni- 

 ferous and Permian strata. In the course of the Garroch Water, red 

 and liver-coloured sandstones,'probably of carboniferous age, are over- 

 lain by red ashy breccia, composed of Silurian fragments and blocks of 

 amygdaloidal lava, followed by slaggy diabase lava. In the Sanquhar 

 basin also there are several " necks " or volcanic rents filled with agglo- 

 merate, which in all likelihood mark the site from which lavas of 

 Permian age were discharged. There is also a small out-lier of diabase 

 lava, resting on the coal fields north of the town, which is regarded as 

 of Permian age. Further evidence might be adduced of the original 

 extension of Permian or Triassic rocks over areas from which they have 

 been removed by denudation. Some of the carboniferous strata in the 

 Sanquhar coal fields have been stained red by the infiltration of iron 

 oxide, and the same feature is observable in the Silurian rocks round 

 the margin of the Thornhill basin. The shales over-lying the Canobie 

 coals have been so much reddened as to resemble externally Permian 

 or Triassic rocks. In these cases the older rocks were formerly buried 

 underneath red sandstones, from which the percolating water derived 

 the iron oxide. 



Between Canobie and Annan there is a strip of red sandstones and 

 marls, which have been correlated with the Triassic sandstones on the 

 south side of the Solway Firth. In the latter region, to the west of Car- 

 lisle, they are succeded by Liassic strata. 



Several prominent basalt dykes traverse the Silurian and Permian 



