414 T. V. Holmes — Geological Structure 



We may now turn from the beds overlying the St. Bees Sandstone 

 to that rock itself and to the Permo-Triassic formations underlying it. 

 They extend not only around Carlisle but up the Eden Valley as far 

 as Kirkby Stephen, and are seen on the coast of Cumberland and 

 Westmorland from St. Bees Head southwards. But those on the coast 

 do not here concern me, nor do the beds of the Eden Valley demand 

 more than the briefest mention. 



In the Eden Valley district, for some miles from Wreay southward, 

 there are three formations in the following order : — 



St. Bees Sandstone. 

 Gypseous Shales. 

 Penrith Sandstone. 



But north of Wreay and Cumwhitton, south-east of Carlisle, lines 

 of fault cut off these Gypseous Shales with the underlying Penrith 

 Sandstone, while the St. Bees Sandstone overlaps them and is the 

 only one of the three formations to be seen north of these lines 

 of fault in Cumberland. North of the Solway St. Bees Sandstone 

 appears, near the shore, as far west as Annan. West of Annan may 

 be seen Lower Carboniferous rock. And from Caerlaverock Castle, 

 up Nithsdale, is another Permo-Triassic district, the conspicuous 

 rock between Caerlaverock Castle and the town of Dumfries much 

 resembling the Penrith Sandstone. 



We have thus in the country bordering the Solway three districts 

 of Permo-Triassic rocks — that of Nithsdale on the north-west, that of 

 the Eden Valley on the south-east, and the Carlisle Basin in the 

 centre. The last-named, extending, as we now know it does, from 

 the information given by Mr. Lamplugh as to the deep borings in the 

 Isle of Man, evidently occupies much the broadest area. 



We are here concerned only with the Carlisle Basin. The lowest 

 of the Permo-Triassic rocks forming this Basin is the St. Bees 

 Sandstone, though possibly very deep borings might reveal the 

 existence of fragments of still older Permo-Triassic rocks beneath it, 

 here and there, as in the north of the Isle of Man. North of the 

 junction with the Eden Valley series, near Wreay, the St. Bees 

 Sandstone is the oldest Permo-Triassic rock . visible in Cumberland. 

 From Maryport to a point south of Wigton it rests on Coal-measures, 

 and thence to Wreay on Lower Carboniferous rocks. Then the lines 

 of fault already mentioned separate it from the Permo-Triassic rocks 

 of the Eden Valley, and eastward and northward it rests upon Lower 

 Carboniferous beds, both on the Cumberland side of the Border and 

 north of the Solway as far west as Annan. Erom Annan towards the 

 south-west it is beneath the level of the sea. Its dip between 

 Maryport and the Caldew usually varies from north to north-west. 

 Between the Caldew and the Blether Burn it slowly changes, being 

 about south-west at the latter stream. North of the Solway it 

 becomes more or less east of south. West of the Esk and at Annan 

 it is nearly due south. 



It has always appeared to me that (as just stated) the St. Bees 

 Sandstone is the lowest Permo-Triassic formation forming the Solway 

 Basin, though it is possible that (as in the Isle of Man) a thin and 



