^{page 435 note 1} Perhaps I had better here explain a few North-country words which occur in this paper, and which may not be generally known.

Whin.—Sometimes applied to any very hard bed, as a hard close-grained sandstone, but more especially to hard crystalline rocks, as the Cleveland Basaltic Dyke, and the great mass of stratiform Basalt that occurs in the North of England. This name perhaps comes from the sound the rock makes when flying off under the hammer.

Sill.—Any bed of rock lying more or less parallel with the neighbouring bed, e.g. the “Slate Sills ” and the “Coal Sills” are particular beds of sandstone in the Yoredale Series. The word is probably connected with the word “sole” (the sole of the foot), and means anything lying flat.

Plate.—Shale.

Post.—The horizontal bands in any bed which are prominently developed on weathering. There is a limestone in the Toredale Series called the “Single Post” limestone, and it gets its name from the fact that very commonly it does not show any horizontal division lines at all, but remains united in one mass in its whole thickness.

Syke.—A stream, or beck.

Girdle Beds.—Alternations of thin sandstones and sandy shales.

^{page 435 note 1} This section is noticed and figured by Sedgwick in the paper already alluded to: he notices it as being specially interesting because:—1. The Whin is not parallel to the beds on which it rests. 2. The limestone has been altered into a saccharoid condition by the Whin. To these we may add: 3. Of the occurrence of Garnets, Prehnite, and Rutile(F) in the Whin, near its surface. 4. Of showing very well the bending round of the master joints in the Whin, as its base changes from a horizontal to an inclined position; the joints always keeping perpendicular to the base of the Whin.

^{page 435 note 2} The limestone a is probably the top of the Melmerby Scar Limestone.

^{page 435 note 3} That these surfaces are original is made out by—1. The extremely fine grain of the Whin. 2. The occurrence of Garnets and Pyrites, on or near them. 3. The presence of bits of altered rock clinging to them in places.

^{page 438 note 1} The limestone b is the second thick limestone below the Tyne Bottom limestone; it is about 130 ft. below it.

^{page 439 note 1} It is probably a little lower, because, as indicated in the diagram, the Whin base seems to have run down slightly towards the South in one place.

^{page 441 note 1} “Green Rock” is the local name for intrusive sheets of basalt in the South Staffordshire Coal-field.

^{page 443 note 1} It is true that if we simply regard the more ordinary sedimentary rocks, limestones, sandstones, and shales, we should find in them, when compared with most igneous rocks, a decided deficiency in the alkalies. But we have also to call to mind the great beds of Rock Salt (NaCl), Carnallite (KC1, MgCl₂, 6 H₂O), etc., which exist in many places.

^{page 443 note 2} The late Rev. J. C. Ward has already, in reference to the Eskdale and Shap Granites, raised the question whether an altered rock may not have a sharplydefined margin (Q.J.G.S. vol. XXXi. No.124, p.592).

^{page 445 note 1} Curiously enough it is never once seen in the Dale immediately below the Tyne Bottom Limestone, although this is the position ascribed to it by those who advocate its contemporaneous character.