118 Mr. Winch on the Geology of the Banks of the Tweed. 



angles, some beds rather exceeding than falling short of 45°. The suite 

 comprises Dolomite, indurated Marl, and Limestone containing Gypsum, 

 Red and Variegated Sandstone, with nodules of Red Ochre, Bituminous 

 Shales and Sandstones, with vegetable remains, Encrinal Limestone, 

 also with vegetable exuvige. Shale, with bivalve shells, and numerous 

 beds of Coal ; the whole series appearing to rest upon Transition Rocks, 

 which, to the north-west and south-west form the Lammer Muir and 

 Cheviot range of mountains. 



At the distance of sixteen miles, in a direct line from the sea, and in 

 the vicinity of Carham (see Map, No. 1.), a small burn enters the Tweed 

 on its south side, dividing Northumberland from Roxburghshire. Here 

 a bed of close-grained iron-grey Basalt occupies the bed of the river for 

 a considerable distance, and near Carham Church rocks of pale-brown 

 Dolomite may be seen on its banks. This Limestone seems to be supe- 

 rior to the Basalt, and is heaped together in irregular masses, but that 

 these are a part of a regular stratum is evident, for at Haddon Rigs, a 

 mile south from this place, the stone is quarried to the depth of ten feet 

 for agricultural purposes, though, from the veins of reddish-brown Chert 

 which pervade it, the produce of pure Lime is much diminished. Be- 

 sides Chert, Calcareous Spar occurs in the rock, which, at the quarry just 

 noticed, is about ten feet thick, with a covering of ten feet of soil. The 

 next point where rocks are exposed to view is on the north side of the 

 river ; at the foot of Spring Hill, about a mile west of Birgham (see Map, 

 No. 2.). Here numerous thin strata of soft arenaceous Limestone, of 

 an ash colour, interstratified with greenish-grey indurated slaty Marl, 

 mixed with Sand and Mica, form cliffs of nearly sixty feet high, and the 

 •river flows over strata of the same description. In this Limestone veins 

 of flesh-coloured compact Gypsum* and nodules with crystals of brown- 

 ish-red Selenite are tolerably abundant. The rocks lie very regular, and 

 dip, at a trifling angle, to the south-east. The relation they bear to the 

 Red and Variegated Sandstones will be noticed when the strata situated 

 lower down the Tweed come under consideration; 



* Gypsum is also found at Fluers, some miles higher up the Tweed, on its north bank, 

 and by the Rev. A. Baird, on the banks of the Whiteadder, near Hutton Hall. — Geologi- 

 cal Essay on Berwickshire, in the Preface of Johnston's Flora of Berwick, page xxi. 



