194 RICHARDSON : THE LOWER OOLITIC ROCKS OF YORKSHIRE. 
thin and the feature that it makes is dwarfed by that produced 
by the outcrop of the underlying Crinoid-Grit of the Scarborough 
Beds ; but in the western portion of the main upland mass that 
lies to the south of a line drawn east and west along the Esk, 
both upper and lower divisions are normally developed. The 
Moor-Grit there, however, admits of the following sub-division : 
(1) into an upper part, which varies considerably and contains beds 
of quartzite, whose detached fragments weather white and dot 
the moorland ; and 
(2) a lower part, which remains a solid white free-stone, well-bedded, 
easily worked, very durable and hardening on exposure, but in 
a few cases, as on Bilsdale West Moor, Hawnby Moor, etc., is 
partly of gannister nature. 
South of the line referred to above as dravm westwards from 
Gristhor23e, the Upper Estuarines are found in the Howardian 
Hills, where they are about 50 feet thick, and have an occasionally- 
indurated bed of sand at their base to lithically represent the 
Moor-Grit. In the neighbourhood of the Derwent, the beds are 
much the same ; while in South-east Yorkshire they comprise 
sands and clays from 20 to 30 feet thick. 
As regards fossils, the Upper Estuarines are unfortunately 
singularly barren and but for a plant-bed in the lo\^'er portion, 
such as is seen at Scalby Xess, between Scarborough and Cloughton, 
would have proved barren in the extreme. The only molluscan 
remains recorded hitherto have been some ill-defined casts of a 
species of Anodon or may be of a Pleuromya at the ver}' base. 
The Upper Estuarines, as already noted, occur between the 
Cornbrash and Scarborough Limestone. The newest portion 
of the latter that has been definitely dated is of blagdeni hemera. 
Hence it follows that the Upper Estuarines occupy the same 
stratigraphical position as the Top-Beds of the Inferior Oolite 
and the deposits of the Great-Oolite Series (be they mainly clay 
or mainly hmestone) of the South-west of England. I have not 
visited the Lincolnshire sections of the Lower Oolites yet and so 
have to rely upon the observations of others, but Mr. Ussher 
thinks that the evidence favours the view that in North Lincoln- 
shire the Great-Oolite Limestone Jms attemiated and died out, and 
that the Upper Estuarines of that part have come into contact 
with the Blisworth or Great-Oolite Clay, and that it is the equiva- 
lents of these two deposits combined that make up the Upper 
Estuarines of the Yorkshire coast and moors. 
