CHAPTER I. 
Description of the rocks deposited in water. 
SLATE SYSTEM. 
*1 he lowest stratified rocks visible in Yorkshire, or at any points on 
the line of the Penine chain, are portions of the great system of argil- 
laceous rocks usually classed as grauwacke and clay slate. Since my me- 
moir on these rocks in Craven was presented to the Geological Society 
(in 1827), the researches of Professor Sedgwick and Mr. Murchison have 
cleared away much of the obscurity which involved the history of the 
older sedimentary deposits, and established amongst their higher groups 
a definite order of succession. Nearly all the argillaceous rocks in the 
British islands, inferior to the old red sandstone, may be arranged in the 
following scheme, and it is already probable that the rocks of Brittany, 
the Harz, the Eifel, and Norway may be subdivided in a similar manner. 
Name x nf Formations. 
f d. Ludlow rocks 
Silurian System „ ) c. Dudley limestone .. 
(Murchison) "j b. Caradoc sandstones 
(a. Builth rocks 
Occurrence in the North of England. 
Near Kirby Lonsdale. 
Unknown in North of England. 
Unknown in North of England. 
Supposed to be known in Hibblesdale. 
Grauwacke or f c. Plynlymmon rocks 
Cambrian System 2 4 b. Bala limestone 
(Sedgwick) a. Snowdon rocks ... 
Clay Slate f c. Clay slate 
or 1 J b. Chiastolite slate ... 
Skiddaw System ( a. Hornblende slate... 
In Hougill fells. 
Coniston Waterhead. 
Langdale, Seafell, &c. 
Skiddaw, Grasmere. 
Skiddaw, Bowscale fell. 
Skiddaw. 
Chlorite schist, mica schist, and gneiss, generally occur below the 
slate system, but are scarcely known in the north of England. 
B 
