^{page 485 note 1} Gypsum and anhydrite were probably present on all horizons, as proved by their presence throughout the limestone in the Seaton Carew boring. The Lower Limestones were probably the least gypsiferous, the eastern equivalents of the reef the most, while the segregated and concretionary rocks were in all likelihood impregnated with gypsum, and the hollow oolites of Roker and Hartlepool were originally gypsiferous.

^{page 485 note 2} East and west refer to east and west of the reef.

^{page 485 note 3} The exact nature of the original Upper Limestones is as yet unknown to the west of the reef. They are totally denuded north of a line drawn through Hartlepool. They have been passed through by borings in South Durham, but nothing very definite can be gathered from the description of these. The Upper Red Beds occur to the west of the reef, and the Upper Limestones are gypsiferous and in part oolitic. The concretionary limestones probably do not occur, being represented by gypsiferous rocks.

^{page 485 note 4} Maximum proved thickness as obtained in the Sheraton and Cotefield Close borings. These beds are largely denuded in North Durham and in the south of the county are covered by drift.

^{page 499 note 1} Kuste, E., Geologisches Wanderbuch für Ostthüringen und Westsachsen, p. 141.Google ScholarBornemann, J. G., “Von Eisenach nach Thal und Wuther”: Jahrb. königl. preuss. geol. Landesanstalt, 1883.Google Scholar In 1913 Trechmann and I visited Thuringia in order to compare the Permian rocks of Durham and South Germany.

^{page 499 note 2} Op. jam cit., vol. lxx, p. 259.Google Scholar

^{page 499 note 3} A Vor-reef also occurs in Thuringia (E. Kuste, op. jam cit., p. 141).

^{page 499 note 4} The coarse fragments in this bed are more or less rounded.

^{page 490 note 1} Trechmann, , Q.J.G.S., vol. lxix, p. 213, 1913.Google Scholar

^{page 490 note 2} The hollow spherules in parts of this rock are very irregular, and have been referred to as being pseudo-oolitic and concretionary. The study of the oolites in other parts of the limestone and their microscopic structure prove that both the regular and irregular spherules are ooliths. They are inorganically-formed oolitic limestones formed by the deposition of dolomite round gypsum. When this substance dissolved out the dolomitic spherules was also partly removed. The ooliths with the gypsum still remaining in them from the cores of borings in South Durham show perfect oolitic structure.

^{page 490 note 3} Q.J.G.S., vol. lxxi, p. 65.Google Scholar

^{page 490 note 4} See table giving this correlation in my paper on Permian of North Durham, op. jam cit., p. 254.

^{page 491 note 1} It should, however, be noticed that the line of principal thrusting in the north (i.e. the junction between the Lower and Middle Limestones) is not exposed along the coast in the southern area.

^{page 491 note 2} Lebour, & Smythe, , Q.J.G.S., vol. lxii, p. 530, 1906CrossRefGoogle Scholar; Haselhurst, , Proc. Univ. Durham Phil. Soc., vol. iv, pt. iii, p. 162, 1912Google Scholar; and Woolacott, , “Geology of N.E. Durham and S.E. Northumberland”: Proc. Geol. Assoc., 05, 1912.Google Scholar

^{page 491 note 3} The thrust at Marsden is described in Univ. Durham Phil. Soc. Mem., No. 1, 1909; at Claxheugh and on Down Hills in Trans. Nat. Hist. Soc. of Northumberland and Durham, n.s., vol. v, pt. i, p. 155, 1919; and a detailed account is given in my paper on the northern area of the Durham Permian, Proc. Univ. Durham Phil. Soc., vol. iv, pt. v, 1912.

^{page 492 note 1} Q.J.G.S., vol. lxii, p. 530, 1906.Google Scholar

^{page 492 note 2} Haselhurst gives evidence proving the pressure was from the north at Cullercoats, Univ. Durham Phil. Soc., vol. iv, pt. i, 1910–11, and I prove that the movement at Marsden was from the north-east.

^{page 492 note 3} Flow-structures occur in the Coal-measures at Whitley, in the limestone above the thrust-plane at Hendon, in the Yellow Sands at Claxheugh, etc., but never on a large scale.

^{page 492 note 4} Van Hise, “Principles of North American Pre-Cambrian Geology”: Sixteenth Ann. Rep. U.S. Geol. Surv., p. 589, and Leith, Structural Geology, p. 3.

^{page 492 note 5} Memoir on Marsden area, op. jam cit., p. 5.

^{page 493 note 1} Fuller evidence is detailed in my memoir on the Marsden district, my general paper on the Permian of North Durham, and the paper in the Proc. Geol. Assoc. Photographs of many of the structures described will be found in these.

^{page 493 note 2} See section, fig. 10, in Permian of North Durham.

^{page 494 note 1} i.e. permanent change of form without conspicuous fracture.

^{page 494 note 2} See section of Claxheugh in Trans. Nat. Hist. Soc., op. jam cit., 1919.

^{page 494 note 3} A general section of the coast is given in my paper on North Durham, fig. 9.

^{page 494 note 4} Memoir on Marsden, p. 10. Sorby showed that this structure had been impressed on Devonian Limestones by pressure “On Slaty Cleavage as exhibited in the Devonian Limestone of Devonshire”: Phil. Mag., vol. xi, p. 20; vol. xii, p. 127, 1856.Google Scholar

^{page 494 note 5} Leith, Structural Geology, p. 10.

^{page 495 note 1} Memoir on Marsden, p. 5 and photograph.

^{page 495 note 2} I regard the breccia of Jean Jiveson's rock as being directly connected with the thrust-plane at Hendon about half a mile to the north.

^{page 496 note 1} Woolacott, , Geol. Mag., 03, 1919, pp. 164–5.Google Scholar

^{page 496 note 2} Similar rocks have been noticed by L. M. Parsons in Carboniferous dolomites. “Dolomitization and Leicestershire Dolomites”: Geol. Mag., 1918, p. 250.Google Scholar

^{page 496 note 3} King, , Monograph of Permian Fossils, Pal. Soc., 1849.Google Scholar

^{page 496 note 4} Broken up segregated rocks of the first two types occur on the eastern flanks of the reef. Vertical slickensided surfaces produced by the slipping down of these beds have been noticed by Trechmann.

^{page 496 note 5} Shattered rocks of this type occur in the Marsden area and in the Claxheugh and Boldon Hills districts.

^{page 496 note 6} These are all best developed in the Marsden district.

^{page 496 note 7} The very coarse breccias south of Seaham Harbour where brecciation associated with faulting is extensively developed are probably the best example of this type.