413 
Geology, 
There are only two systems relating to the explanation 
of the general appearance of our planet, that are entitled 
to any consideration : the one the Neptunian , at the head 
of which is Werner the professor of mineralogy at Fri- 
burgh ; the other the Plutonian ?, advanced by the late Dr. 
Hutton, so well known in the mathematical world, and at 
present chiefly supported by professor Playfair of Edin- 
burgh. 
Werner’s system, in brief, is, that all the more exten- 
sive and universally-found strata, or formations, of our 
globe, have been formed, partly by crystallization of sub- 
stances dissolved or intimately mixed with the watery 
fluid that contained them in a chaotic state— partly by 
subsidence of the particles mixed with the water — and 
in cases of volcanic strata, by volcanic eruptions. His 
general distinction of primitive, transition, secondary, 
alluvial, and volcanic soils or rocks, appears to me too 
probable to be rejected ; nor is it possible for any person 
who has seen, (as may very commonly be seen,) granite 
and quartz ; also plants and soft shells, surrounded by 
and enveloped in* limestone, flint, siliceous grit, and ar- 
gillo-silite, to doubt, but the great majority of rocks and 
stones, are formed by crystallization and subsidence of 
particles dissolved or mixt in water. 
According to the Plutonian hypothesis of Hutton and 
Playfair, our globe is subject to a gradual but perpetual 
change, inducing endless alterations of continent and of 
sea, in the same places. The present continents, for in- 
stance, are subject to destruction by the action of air, 
rain, mechanical attrition, chemical decomposition, the 
operation of gravity, &c. Tl?e materials thus broken 
down, and decomposed, are gradually carried to the bot- 
tom of the ocean, where they are subject to induration 
by the action of internal heat, and new strata are formed, 
which in time are raised by subterraneous fires, beeoim 
