feet of Lower Lias is exposed, and the symmetrical terraces formed by the sandy beds of the Middle Lias, and the jet rocks of the Upper, form marked features in the valleys, especially on the southern slopes. FIG. 2.-VERTICAL SECTION OF LIASSIC AND OOLITIC SERIES. The moorlands, which form the watershed between the Esk and the tributaries of the Derwent, are coincident with an anticlinal, the rocks on the north having a northerly dip, whilst those on the south dip in a southerly direction. The streams draining southwards have cut through the sandstones and intervening shales in a similar manner to those falling to the Esk, and deep dales exhibit the Liassic beds in a very instructive manner; they are Rosedale, Bransdale, Farndale and Bilsdale. Further south the streams have deeply indented the Coralline Oolites of the Tabular Hills, and carved their way through them to the Vale of Pickering beyond, where the streams are known as the Rye, Dove and Severn, their combined waters join the Derwent a few miles above Malton. It is proposed to describe with more or less detail three sections which serve to illustrate the whole series of the Liassic and Oolitic Rocks which occur in Yorkshire. First the section exposed in Robin Hood's Bay and Peak, which comprise the Lower, Middle, and Upper Liassic Strata, the Dogger Beds and the Estuarine Series of the Lower Oolites, as high as the Grey Limestone Series. Second: the section exposed in the Gristhorpe Cliffs which includes all the beds between the Millepore beds of the Middle Estuarine Series, and the base of the Coralline Oolites; and third, the Scarborough Castle and Hackness sections which expose the Middle Oolites from the Cornbrash and Kelloway Rock to the Upper Calcareous Grits I.—SECTIONS AT ROBIN HOOD'S BAY AND PEAK. The LIASSIC BEDS are well developed in Robin Hood's Bay and the Cliff between Blea Wyke and Peak Steel. The oldest beds occur only in the scars furthest from the shore, about the middle of the Bay (fig. 3). Succeeding beds higher in the series occur in the scars of the Bay and in the Cliffs. They give place to the Middle Lias, the Marlstone of Prof. Phillips. The Middle Lias consists of two parts, the Lower or Sandy Series, well exposed at the North Cheek of the Bay and on the west side of the Peak Fault. The Upper part, named the Ironstone Series, forms the triangular mass of rock between the forks of the Peak Faults; a complete section is also exposed in the cliff at Hawsker Bottom (fig 5). The Upper Lias consists of three divisions. The Lowest, a soft grey shale; the Middle, a hard dark shale with doggers: and the Upper, the Alum Shale, with beds of hard jet rock at its base. These beds of the Upper Lias may be studied in the cliffs west and east of the Fault; on the west, high up in the cliffs at and near the Peak Allum Works; and on the east, thrown down to the foot of the cliff and the scars at Peak Steel. It is proposed to give a description of the several beds, which are admirably exposed for observation, perhaps nowhere elso so well, in Robin Hood's Bay and Peak. OSTATUS ROBIN HOODS BAY BUCKLAMOR TURNERY JASMITTARIUS LEAGATEUS FIG. 3.-SHORE-PLAN IN ROBIN HOOD'S BAY, SHOWING THE POSITION OF THE LIAS-ZONES. The LOWER LIAS is more extensively exposed in the scars and cliffs of Robin Hood's Bay than elsewhere in Yorkshire. The lowest beds containing Ammonites planorbis do not occur in Yorkshire, but, as Professor Blake has pointed out, it probably occurs in the bottom of the North Sea, because hard calcareous nodules are constantly being washed upon the shore, which contain that fossil in excellent preservation. The next zone, Am. angulatus, is exposed at Redcar, and the succeeding beds, in the district under consideration. The rocks here consist of argillaceous shales, slightly sandy and of a dark colour, with bands of hard marl in the lower part. The Lower Lias may be divided into the following beds, each characterized by a distinct fauna. B. Soft shales with rows of ironstone doggers d. Soft shales with rows of ironstone doggers. (Zone of Am. Capricornus) Gryphaa obliquata. and pyritous nodules. c. Soft shales with rows of pyritous 320ft. nodules. (Zone of Am. Jamesoni) G. obliquata, Pinna folium. A. Soft shales with a suc cession of sandy and marly bands. 140ft. b. Shales with hard sandy bands, the a. upper parts covered by fucoidal markings. (Zone of Am. oxynotus) Gryphaa incurva, Ammonites abundant. Shales with marly calcareous bands, generally very shelly. (Zone of Am. Bucklandi) Gryphaa incurva, Hippopodium ponderosum in bands, Am. semicostatus. The zone of Ammonites Bucklandi (a) forms a series of outer scars in the Bay parallel with the coast line, and dipping at an angle of 4° to the S.S.W. The outcrop is about 300 yards in extent, and the rock consists of soft grey shales with harder calcareous sandstones interspersed. They are only exposed at low spring tides, and are rendered difficult to investigate by the quantities of seaweeds which is attached to the beds. It is only after the hot summer weather has to some extent destroyed the weed that they can be examined satisfactorily. The following is a list of the principal fossils found in these beds :Gryphæa arcuata, Lam. Lima Hettangiensis, Terg. Monotis inæquivalvis, Sow. Pecten calvus, Goldf. Lucina limbata, T. & B Dentalium etalense, Terg. & P. Ammonites Bucklandi, Sow. The Ammonites Oxynotus Zone (b) is about 110 feet in thickness. it consists of alternating layers of soft shale and bands of sandy marl, the latter being remarkable for impressions of fucoids which are rendered visible by exposure to sea-water. Fossil ammonites are |