34 THE MEDALS OF CREATION. Cuap. Il. 
unknown. No vegetable relics, excepting Fuci, have béen found in 
Britain below the Devonian or Old Red formation.* 
The Camprian Formation. This term is applied to a 
largely developed series of unfossiliferous slate-rocks and — 
conglomerates, many thousand yards in thickness. 
Obs.—Certain beds of dark-coloured schists containing a few corals, 
f 
? 
fuci, and shells, are referred to the uppermost part of this formation 4 
by some eminent geologists, but it is more consonant to the esta- Bi 
blished system of classification to regard these fossiliferous beds as the : 
lowermost of the Silurian rocks. The fineness of grain, general aspect, 
hardness, and texture of these strata, are well known, from the general 
employment of slate for economical purposes. These rocks extend 
over a great part of Cumberland, Westmoreland, and Lancashire, — 
reaching to elevations of 3,000 feet, and giving rise to the grand — 
scenery of the Lakes, and of North Wales. 
dppogene Mocks. (Wond. p. 806.) 
Non-fossiliferous. 
Metamorpuic (transformed) or stratified crystalline rocks. — 
Subdivisions.—1. Mica-schist System. (Wond. p. 843.) j 
Probably sedimentary rocks altered by high temperature. — 
Mica-slate, Quartz-rock, Crystalline limestone, Hornblend | 
schist, &c. 
2. Gneiss System. Layers of Gneiss, Sienite and Quartz- 
rock, alternating with Clay-slate, Mica-schist, &e. 
ee a cc 
Puutonic Rocks; unstratified crystalline masses. 
Granatic System. (Wond. p. 844.) Granite—a rock com- 
posed of mica, quartz, and felspar ; Porphyry ; Serpentine ;_ 
Trap. These rocks occur in amorphous or shapeless masses, 
and in dykes and veins. 
feo hat at Dyctage vee 
* “THE SILURIAN SysTEM” contains excellent figures of all the 
f 
organic remains known at the period of its publication. | 
