28 
MEMOIR OF WERNER. 
quired the most intimate acquaintance with these 
laws, and could read in them the history of all the 
revolutions from which they had resulted. Follow- 
ing each bed in the order of its continuity, without 
allowing himself to be bewildered by rents and shift- 
ings, or by tbe crests and other summits which rise 
above them, he in some measure determined their 
age, and the age of all the accessory matters which 
intermingle with their principal substances. 
Tbe different fluids which have surrounded the 
globe, the changes in composition which they have 
undergone, and the violent commotions by which 
each change has been accompanied, were all legible 
to bis eyes on the monuments wdiich they have left 
behind them. 
A universal and tranquil ocean deposites in large 
masses the primitive rocks, which are strongly crys- 
tallized, and have silica for their predominating in- 
gredient. Granite forms the base of the whole. To 
this succeeds gneiss, which is nothing more than 
granite beginning to assume a slaty structure. By 
degrees, argil begins to predominate. Schists of 
different kinds appear ; but in proportion as the pu- 
rity of the precipitations becomes changed, the dis- 
tinctness of the crystalline grain diminishes. Ser- 
pentines, porphyries, and traps succeed, in which 
tbe grain is less distinctly formed, although a sili- 
ceous nature begins to resume its purity. Internal 
agitation in the fluid destroys a portion of these pri- 
mary deposites; and their debris forms new rocks. 
