W. IT. Hudkston — On the Yorkshire Oolites. 149 



Hills, worked in Whitwell parish and elsewhere, are referred to tliis 

 horizon. North of Scarborough, on the coast, 100 ft. of " estuarine " 

 sands and shales, containing the principal moorland coal and the 

 celebrated plant-bed, intervene between the Millepore-Bed, and 



3. The third zone, known as the Scarborough or Grey Limestone. 

 South of Scarborough these two zones approach, the Millepore Bed, 

 as we have seen, becoming thicker, whilst the Scarborough Lime- 

 stone in Gristhorpe Bay is reduced to a few feet, with every indication 

 of going out altogether. Thus it is the Millepore-Bed which 

 reappears further south as the Cave Oolite and the Lincolnshire 

 Limestone. Near Scarborough, however, and especially north of 

 that town, the uppermost of these two formations is far the most 

 important. On the south horn of Cloughton Wyke, at Hundale, this 

 group of beds has a thickness of nearly 60 feet, and contains a fine 

 series of fossils, chiefly Conchifera. On the other side of Scar- 

 borough, at White Nab, the thickness has already fallen to 20 feet. 

 It is here that specimens of Am. Humphresianus and Blagdeni have 

 been found together with casts of a large Chernnitzia eind Phasianella.^ 

 Lithologically this zone is composed for the most part of blue-grey 

 limestones, more or less charged with dark-coloured mud, and in 

 places is rich in iron. The fossils partake of this grey character, 

 but there is a little difficulty sometimes in distinguishing specimens 

 from certain varieties of the Millepore or Cornbrash. This is the 

 least oolitic in structure of all the four zones of the Lower Oolites. 



The three zones enumerated above belong to the Inferior or Bajo- 

 eian subdivision of the Lower Oolites. The two lowest {i.e. the 

 Dogger and the Millepore) are probably both in the MiircMsonce 

 zone, the Millepore occupying the subzone of Ammonites Sowerbyi, 

 though no ammonite has ever been found, to my knowledge, in beds 

 of this horizon on the coast. The Scarborough Limestone, which 

 distinctly dies out on the dip, must be regarded as on a level with 

 the Coronaten-zone of the Germans. Above this comes a third 

 " estuarine " series, which also thins considerably on the dip. As 

 we have no palseontological indications in Yorkshire either of the 

 FarJcinsoni-zone,'^ or of the Great Oolite, it is not unreasonable to 

 suppose that this third estuarine series may represent those forma- 

 tions in time. The gradual attenuation of the Great Oolite (Batho- 

 nian) in Lincolnshire ^ as a marine formation prepares us for this 

 change. Doubtless the Yorkshire Cornbrash must be regarded as 

 the only representative of Bathonian beds in a palEeontological sense, 

 and this constitutes our 



4. Fourth zone, only three or four feet thick at Scarborough, but 

 extremely fossil iferous. It corresponds to part, at least, of Dr. 

 Brauns' " Oolithischen mergel und eisenkalke mit Avicula echinata." 

 The fossils from this bed are at once recognized by a peculiar waxy 



1 For details of the sections at Hundale and White Nab see " Yorkshire Oolites," 

 part i. Proc. Geol. Assoc, vol. iii. p. 312 et seq. 



2 Am. Farkinsoni, Sow., is quoted by Phillips from the " Grey Oolite " of "White 

 Nab, G. Y. third edition, p. 267, but I have never seen it in any collection. 



3 Judd, "Geology of liutlaud," p. 10. 



