92 Reports and Proceedings. 



these beds have a thickness of 700 feet, mostly sands and shales, 

 nearly devoid of marine mollusca, but rich in plant remains. There 

 are, however, four distinct zones of marine life (well pointed out by 

 Dr. Wright in 1859), which may be made out on the coast, and 

 identified in the transverse valleys of the Moorland range. 



1. The Dogger and its associated Sandrock, magnificently de- 

 veloped at Blue Wyke, a sandy Oolite altered into an ironstone, 

 calcic carbonate being replaced by ferrous carbonate ; in the case of 

 the shells the original material being now replaced by siderite. Very 

 unequally developed, it sometimes rests on 60 feet of Striatidus-heds, 

 sometimes directly on the Upper Lias, and is considered by geologists 

 as forming part of the Murchisonia zone of the Inferior Oolite. It is 

 the source of the principal Oolitic ironstones of Yorkshire. The 

 Eosedale magnetic ore is a local boss occurring in the underlying or 

 Blue Wyke Sands. Fossils are usually small of their kind, and 

 mostly come from the Nerinasa-bed. 



2. " The Millepore-bed." — At the point of their maximum de- 

 velopment, 300 feet of sands and shales intervene between the 

 Dogger and this bed, which, north of Scarborough, is usually an 

 arenaceous ironstone, but a few miles south of that town becomes 

 the most important calcareous member of the Lower Oolites. 

 Ceromya Bajociana, Modiola imbricata, and Pinna cuneata are very 

 common shells, whilst Pholadomya Loemanni and Fygaster semisul- 

 catus are characteristic; but the author was unable to find any 

 Brachiopods. 



The principal fossiliferous bed is an Oolitic marl, altered into an iron- 

 stone ; the shell matter is gone, and partly replaced by a kind of Kaolin. 



3. 100 Feet of Sandrock succeed, and then follows the " Scar- 

 borough Limeston-e" series, consisting of grey marly limestones, 

 alternating with marly shales, varying in thickness from 50 feet at 

 Hundall to three feet at Gristhorp (distance nine miles). Belemnites 

 giganteus is a conspicuous fossil. A few specimens of Ammonites, 

 Blagdeni, etc., have rarely been found in nodules. Avicula, Gervillia, 

 Pinna, extremely abundant. Trigoma costata fine. Trigonia signata 

 rare. No Brachiopoda, and only species and fragments of Echino- 

 dermata. Above the " Scarborough Limestone" series occur 160 feet 

 of shales and sandstones ; some of these beds exhibit casts of 

 Myaciform shells. There is also a ferruginous bed containing an 

 oval Unio of moderate size in great abundance. 



4. The fourth fossiliferous zone is usually referred to the Cornbrash. 

 More complete marine conditions are apparent. Brachiopoda are 

 abundant. Ammonites Herveyi plentiful. A fine suite of fossils were 

 obtained from this bed, which is the last of the Lower Oolites. 



In the inland chain S.W. of the Vale of Pickering, the Lower 

 Oolites are much attenuated, amounting to more than 150 feet in the 

 Derwent valley. The types, too, are much altered. At the base 

 resting on the Lias is the " Top-seam " of ironstone, with Lingula 

 Beanii and Orbicida reflexa on the horizon of the sands of Blue 

 Wyke, which are also further represented by an argillaceous lime 

 and iron stone, containing species of Glyphcsa, similar to those found 



