Mr. Winch on the Geology of the Banks of the Tweed. 17 



shore of the Tweed the whole way to the harbour, but on the 

 north bank, Berwick Castle stands upon an elevation about 

 ninety feet high. Under the soil the rocks are variegated and 

 red sandstones, of extremely fine-grained texture; the beds 

 are thick, in which they may be compared to the posts in this 

 part of our district, while the thin calcareous strata occupy 

 the place of our metals and bituminous shales ; but so consi- 

 derable a proportion of carbonate of lime do all the sandstones 

 hereabout contain, that they effervesce on the application of 

 diluted mineral acids. The dip southward of east. From, 

 the rocks on which Berwick Castle is constructed to the en- 

 trance of the harbour the space is covered by soil ; but both 

 towards the north and south high and rugged cliffs bound 

 the ocean. Those to the north shall first be brought under 

 consideration. On passing through the Sally-port, and be- 

 fore reaching the Pier, the following succession of rocks rise 

 to the day: 1st. A thick stratum of fine-grained brick-red 

 micaceous sandstone. 2d. Hair-brown limestone, with small 

 encrinites. 3rd. Slaty micaceous sandstone, of an ash-gray 

 colour. 4th. Red sandstone. 5th. Encrinal limestone. 6th. 

 White sandstone, blotched by red ochre and containing coal 

 pipes. 7th. Encrinal limestone. 8th. Slaty micaceous sand- 

 stone. 9th. Encrinal limestone. 10th. Variegated sandstone. 

 These strata occupy the space from the Sally-port to the Pier. 

 The limestones are of inconsiderable thickness, and envelope 

 bivalve shells as well as encrinites. The red and variegated 

 sandstones are very fine grained, with but little mica ; and the 

 coal sandstones white, when not tinged by yellow ochre. 

 At this point, which may be about a hundred yards north of 

 the Pier, a slip dyke, of considerable magnitude, intersects 

 the cliff, and may be traced eastward into the sea; its breadth 

 is three yards, the south side of the chasm being filled for 

 two yards by shale, and the north side by a rib of brownish- 

 purple limestone, so hard as to give fire with steel ; it is of a 

 fine texture, with a splintery fracture, and impressions of the 

 lanceolate leaves of some species of Variolaria of Ad. Bron- 

 gniart, Stigmaria of Sternberg, are dispersed through it. The 

 hade of the dyke is inconsiderable, but to the south of it the 

 strata dip to the south-east at an angle of 45. A little to the 

 north, the rocks become less inclined, and dip to the east at 

 a trifling angle; the upper is a stratum of ash-coloured shale, 

 twelve feet thick, filled with Producti (Productus scoticus, 

 Sowerby, Mineral Conch, t. 59, f. 3 ; and Productus anti- 

 quatus, t. 317, f. 1, 5, 6.), the shells of which retain their 

 pearly lustre; the lower stratum is encrinal limestone, in- 

 closing specimens of very large Producti (Productus gtgan- 

 N.S.Vol 9. No. 49. Jan. 1831. D tens, 



