21 
and to suggest the means to he employed in tracing the links of connec- 
tion and relations between them. For this purpose it will not be needful 
here to enter into the details of the geography and condition of each of the 
different river basins -which the county includes. My own attention, from 
residing in the midst of it, has been more especially directed to the north 
riding ; the surface of which embraces almost as wide a range of variation 
as that of the whole county, and has been ascertained to produce all but 
46 species which the county affords. I have therefore selected it for 
illustration, and will proceed to give a brief and cursory account of the 
prominent features of the respective districts which it comprises. I 
would refer those who may wish to study the physical geography of the 
county to the various works on the subject by Professor Phillips, especially 
his latest, “ The Rivers, Mountains, and Seacoast of Yorkshire,” from 
which many of the facts here brought under consideration have been 
obtained. 
As has been already explained in the Flora, the north riding consists of 
a broad central vale, running north and south, between two groups of 
hills, the eastern range of which has also a smaller depression both on 
the north and south. Of these, the western series is the most extensive 
and attains the highest elevation. The general slope of the surface is : 
from west to east, and consequently the general flow of the river is in the 
same direction. With the exception of a small tract of greenstone at the 
north-western corner of the county, and a few inconsiderable veins and 
dikes of plutonic origin, the mineral masses of the surface are all sedi- 
mentary, and have been deposited during the primary and secondary 
periods. In order of succession they are thus arranged from west to east; 
each usually sloping more considerably in that direction than the whole 
mass. 
Names. Localities. 
I. Primary period. 
A. Carboniferous Series. 
1. Scar limestone Cronkley Fell, Micklefell. 
2. Yoredale limestone . Hawes, Muker, Reeth. 
3. Millstone grit Gretadale, Balderdale, Masham. 
B. Permian Series. 
4. Magnesian limestone Bedale, Thorp-arch, Eipon. 
II. /Secondary period. 
C. Trias Series. 
5. New Red Sandstone York, Thirsk, Northallerton. 
