( 177 ) 
explanation of the plates. 
The geological map of the eastern part of Yorkshire is intended to convey a correct 
general idea of the relative situation and extent of the principal mineral masses ; and 
though the scale to which it is drawn does not allow of minute accuracy, the outlines 
will be found sufficiently exact. I claim no merit for introducing the unconformed 
direction of the strata beneath the Wolds, the correct line of the Kimmendge clay, nor 
thatof the Bath oolite formation, because these points have been long since determined 
l v Mr Smith, who will, it is hoped, soon publish the results of his long and successful 
U on a splendid geological map of the county. The colours used on the map 
sometimes 5 include^ a number of strata, which in the section have different tints assigned 
T* The diluvial gravel, clay, &c. of Holderness are represented by a bright 
, but it has not been deemed necessary to mark these accumulations in the vales 
P f York Pickering, and Cleveland. The white chalk is left uncoloured, but the red 
layers at its base are indicated by an appropriate narrow red line. The greenish 
i / adopted from Mr. Smith, represents the great clay formation of the vale of 
of which the upper part corresponds to the gault, and the lower to the 
Kimmeridge clay. The coralline oolite formation occupies the space of the light orange, 
WBie Oxford clay and Kclloways rock beneath range along die line of the dun purple. 
To Hive coloured across the moorlands the sub-divisions of the Bath oolite forma- 
tion which are visible on the coast, would have been hardly practicable , ant re 
method of grouping them, as Mr. Greenough has done has the great advantage of 
exhibiting at once the general analogy of these rocks and those m the south of England 
whilst their differences may be easily gathered from the detailed sections. He g 
oltw includes the cornbrash, upper sandstone and shale, Cave oolite, and lower sand 
y l bale whilst the inferior oolite, or dogger, is marked by the narrow stripe of 
f irorat ‘ The lias formation is coloured blue, and the new red sandstone pink ; the 
VM purple is employed for the diluvium both in the map and in the sections ; 
S a ndAe ri ir colours inYe latter are fully explained by references engraved on the 
plates, which also contain the necessary scales of altitude. 
REFERENCE TO THE PLATES OF ORGANIC REMAINS. 
The specimens figured in the following Plates are ^chiefly m ^he the Author ; a few 
Mr ' Pr£St0n ’ theWhUby 
Museum, as indicated by the name after each species. 
Plate I.— Chalk, page 90. 
Fig. 
l g S p.»giapla«a. 4. Spongia Benetri*. For * , Mu,. 
I P capita... J-W 5 ' n‘ 
8 . ciulifaa. Yorl,.M«. 6 convoluta. D,tto. 
a a 
