4 1 0 THE GEOLOGY OF THE YORKSHIRE COAST BETWEEN REDCAR AND ROBIN HOOD'S BAY. By R. S. HERRIES, M.A., V.P.G.S., President. (Read Jtdy 7th, I906. Some advance copies c-ere printed and issued to Members in]uly. The paper is now reprinted with a few alterations and additions.} HE custom that the DIrector of the "Long" Excursion of T the Association should write a paper descriptive of the geology of the country to be visited has crystallised into a law, otherwise I should have suggested that the admirable paper by Prof. J. F. Blake, * published in illustration of the last visit of the Association to the Yorkshire Coast, in 1891, should be reprinted and distributed as a pamphlet to the members attend­ ing the excursion. Prof. Blake, it is true, deals with "the country between Redcar and Bridlington," whereas my southern limit is Robin Hood's Bay, but I think it will be as well to give a short general sketch of the geology of the Yorkshire Coast as an introduction to that part of it which comprises the exposures of the Lias. I can only begin by quoting Prof. Blake when he says, " After the abundant work that has been done upon this most interesting area by Phillips, Tate, Hudleston, the Geological Surveyors, Lamplugh, and the writer (Prof. Blake), there is little or nothing original to be said on this district." Since this was written the work of Dr. Rowet on the Yorkshire Chalk has been published, as well as the Geological Survey Memoir by Mr. Fox Strangways.] which practically summarises everything that had been written on the subject up to that date. There have been two previous excursions of the Association to the Yorkshire coast. The first was in 1875, and was directed by Messrs. Hudleston, Woodall, and Fox Strangways, Prof. J. Morris, and Sir C. Strickland. On that occasion Whitby was visited, one night being spent there, and the headquarters were afterwards removed to Scarborough. The second was in 1891, under the guidance of Prof. J. F. Blake, Mr. G. W. Lamplugh, and Rev. E. M. Cole, the party staying first at Driffield and then at Scarborough. On that occasion the whole coast from Bridlington to Whitby was included in the programme, as well as such inland sections as Suffield quarries, Pickering, and Newton­ dale. I took part in that excursion, and could not help thinking * "The Geology of the Country between Redcar and 13ridlington," by J. F. Blake, Proc, Geol, Assoc., vol. xli, p. II5. t "The Zones of the White Chalk of the English Coast, Part IV, Yorkshire," by A. "V. Rowe, Proc. Geol. A 550C., vol. xvtll, p. 193. t ;lTh~ ]urassicRocks of Britain, vel, i, Yorkshire," by C. Fox Strangways, R. S. HERRJES ON THE GEOLOGY OF THE YORKSHIRE COAST. 411 that the senior Director, with that superabundance of energy for which he is noted, attempted to get too much into the six days. * I have therefore decided, and I hope I shall not fall into the opposite extreme, to confine the excursion on this occasion strictly to the coast, and to that part of it which lies to the north of Blea Wyke, where the Dogger first appears from under the sea, so as to embrace the whole of the sections of Lias and the beds immediately overlying it. There are two excellent reasons for doing this; the first is that at Easter the Association visited the other great coast sections of Lias at Lyme Regis and the neighbourhood, and it will be a great opportunity for those who are able to attend both excursions to compare the two sections. The second reason is that the Association has never visited the district north of Whitby, which can show a succession of cliff sections of a character almost unrivalled in England, culminating in the great cliff of Boulby, 666 ft. in height, said to be the highest in England. The Yorkshire coast is divided into two distinct parts, of which the northern is- rather the larger, by the prominent projection of Flamborough Head, where the chalk Wolds run out to sea. South of this point there is not a scrap of solid geology to be seen, the whole coast of Bridlington Bay being made up of Boulder Clay, sands, and gravels of the Glacial Series. The northern section is again nearly equally divided between the outcrop of the Cretaceous, Neocomian, and Oolitic beds to the south, and the Liassic sections to the north, the dividing point being Blea Wyke just to the south of Robin Hood's Bay. Another peculiarity about this coast may be noted, and that is its unbroken character. Bounded on the north and south by the two great estuaries of the Tees and Humber, it is only breached in its long stretch of upwards of 100 miles by a single river, namely, the Esk, which runs into the sea at Whitby. The cause of this, which was not always the case, will be discussed later. The geology of Yorkshire, from the Mesozoic period onwards, has so much to distinguish it from other parts of England, that it may fitly be considered as a province apart. The Lias is developed zone by zone in a way that is exceptional, but it does not otherwise present features very different from other parts. Economically it has always been noted, formerly for the alum extracted from the Upper Lias Shales, and for the jet found in the harder beds immediately below, and now for the rich iron­ stone beds of the Middle Lias. When, however, we come to the Lower Oolites we have a great series of Estuarine beds with certain thin but persistent marine beds separating them into • Since these words were written I have received the sad news of the death of Prof. Blake. 412 R. S. HERRIES ON THE GEOLOGY OF THE YORKSHIRE Upper, Middle, and Lower. These marine beds all correspond to different horizons of the Inferior Oolite of the south of England, so that when the Cornbrash is found succeeding the Estuarine beds, apparently without a break, it is clear that the Bathonian, if represented at all, must correspond with the Upper Estuarine or part of it. It is true that these Estuarine beds exist in Lincolnshire and the adjoining counties, though they are not so largely developed. Now when we come to higher beds we find exactly the opposite. While the great deposits of Purbeck and Wealden strata of freshwater or estuarine character were being laid down in the south of England a great marine series was in course of formation in Yorkshire (as well as in Lincolnshire) known as the Speeton Clay, the upper part of which represents also the Lower Greensand of the south. Then again, while the great limestone series of the Bath and Portland Oolites of the south are not represented as such in Yorkshire, the calcareous character of the Coralline Oolite, which all through the Midlands has disap­ peared, reasserts itself with great strength in Yorkshire, whether as grit, coral rag, or limestone proper. The absence of Tertiary Beds is not peculiar to Yorkshire, but may be mentioned to complete the contrast with the south of England. Professor Blake* attributes these striking differences to a separation of Yorkshire from the surrounding districts by an axis of elevation which began to be marked in Carboniferous times, running from the Humber to the Tees, and it seems clear that something of this kind must have been the case. Subjoined is a list of the Cretaceous and Jurassic Rocks as exposed on the Yorkshire coast: Chalk (without flints). Chalk (with flints). Red Chalk (Gault). Speeton Clay (Neocomian). Kimeridge Clay. Upper Limestones } Middle Calcareous Grit Corallian. Lower Limestones Lower Calcareous Grit Oxford Clay. Kelloway Rock. Cornbrash. Upper Shale and Sandstone (Estuarine) Series. Grey Oolite, or Scarborough Limestone. Middle Shale and Sandstone (Estuarine) Series. Millepore Oolite. * Loc. cit., p. II7. COAST BETWEEN REDCAR AND ROBI:-l HOOD'S BAY 413 Lower Shale and Sandstone (Estuarine) Seri es (with Ellerbeck Bed). The Dogger. Blea Wyke Beds . Upper Lias (Shales). Middle Lias (I ronstones and Sandstones). Lower Lias (Shales). We will now consider the successive beds in rather more detail, beginning for convenience from th e south, that is to say, with the uppermost beds, for there is a general southerly dip, so that as we follow the coast northwards we, generally speaking, pass from newer to olde r beds. The Chalk first appears on the coast a little north of Bridlington, and forms the cliffs all round Flamborough H ead to Speeton. This is the end of the range known as the Wolds, which runs up from th e H umber all through South-East Yorkshire till it reaches th e sea at thi s point. As in the south-west of En gland the chalk overlaps various beds in succession from the Lias upwards. The Chalk ranges from the zone of B el. quadratus to th e Lower Chalk which is seen at Speeton. Below the Lower Chalk comes the R ed Chalk, which is generally identified with the Gault of the South of E ngland, and below that is the Speeton Clay, a thick deposit of blue clay, marine in character and very fossiliferous. The intr icate strati­ graphy of th is deposit has been well worked out in th e classic papers of Pr of. Judd * and .l\Ir. Lamplugh.j As I have already stated, it has been classed as Neocomian, and probably represents in time not only the Lower Gree nsand of the south, but also th e Weald en and Purbeck.