RICHARDSON : THP: LOWER OOLITIC ROCKS OF YORKSHIRE. 203 
Ldmestone, which is continuous into South-east Yorkshire, where — 
on account of the attenuation of the portion of the Lower Estuarines 
which comes above — it occurs close under the Cave OoHte. 
Before the deposition of the Lower Estuarines, the Dogger 
appeals to have undergone some channeUing, for in places the 
bottom sandstones of the Lower Estuarines occur in hollows 
excavated through the Dogger and into the Upper Lias. 
The Lower Estuarines have yielded no fossils whereby to 
date them, and therefore their approximate age must be assumed 
to be of the hemerae intermediate between discitce and murchi- 
sonce — that is of bradfordensis and concavi hemerae. 
The Dogger. — This is perhaps the best known of the marine 
bands in the Lower Oolitic Rocks of Yorkshire, and in places 
contains fossils abundantly. It varies considerably from place to 
place both as regards thickness and lithic structure. (Plate XXIV.) 
" It changes," writes Fox -Strang ways, " from a sandstone to a 
limestone or a valuable ironstone, and from a fine-grained shaly bed 
to a nodular calcareous oolitic rock with little bedding. In some 
places it seems to form a passage bed between the Lias and the Lower 
Oolite, in others it rests on a distinctly eroded surface of the shales, 
while here and there it is itself cut out entirely by the Estuarine 
Sandstones, which rest immediately on the Alum Shale." (p. 154). 
At Blea Wyke a bed full of examples of Nerincea and other 
gasteropods and lamellibranchs is its most interesting member. 
Below it is a deposit of sandstone, 25 feet thick, lined with blackish 
nodules, which Hudleston and Herries Avould assign to the Dogger, 
but which I should feel inclined to class with the underlying Blea- 
Wyke Beds. 
Above the Nerincea-Bed at Blea Wyke is more sandstone — 
10 feet of it ; but this succession of sandstone, Nerincea-'Bed, 
sandstone, only obtains on the downthrow side of the Peak fault. 
Scarce half-a-mile away at the Loftus Alum Works, the Dogger 
is quite different, relatively thin, and contains numerous derived 
fossils, many of which are Liassic ammonites. i 
The blackish pebbles in the sandstone above the Nerinoea-Bed 
at Blea Wj^ke, some of which have been identified as rolled Liassic 
fossils, together with those derived specimens in the Dogger of 
the Loftus workings point to some areas having been exposed and 
I Bed 5 in Mr. Herries' record (Proc. Geol. Assoc. Vol. XIX., 1906, p. 425) yielded him a specimen 
that was identified by Mr. S. S. Buckman as Sequenziccras cf. algovianum (Oppel), ? sp. nov. 
(derived); bed, Grammoceras aff. striatulum (J. de C. Sow.), striatiili hemera (derived); 
while specimens of Phlyseogram. cf. dispansum (Lye), dispansi hemera, and P. metallariuni 
(Dam.), also dispansi hemera, were obtained. 
