4 
. 
MODIFIED ly COMPRESSION. 173 
prefent form. In extending that fame influence to periods of 
ftill higher antiquity, when our ftrata lay at the bottom of the 
fea, we do no more than afcribe permanence to the exifting 
laws of nature. 
Tue combination of heat and compreffion refulting from 
thefe circumftances, carries us to the full extent of the Hutto- 
nian Theory, and enables us, upon its principles, to account 
for the igneous formation of all rocks from. loofe marine depo- 
fites. ; 
Tue fand would thus be changed to fandftone ; the fhells to: 
fimeftone ; and the animal and vegetable fubftances to coal. 
Oruer beds, confifting of a mixture of various fubftances, 
would be ftill more affected by the fame heat. Such as con- 
tained iron, carbonate of lime, and alkali, together with a mix- 
ture of various earths, would enter into thin fufion, and, pe- 
netrating through every crevice that occurred, would, in fome 
cafes, reach what was then the furface of the earth, and con- 
ftitute Java: in other cafes, it would congeal in the internal 
rents, and conftitute’ porphyry, bafalt, greenftone, or any other 
of that numerous clafs of fubftances, which we comprehend 
under the name of whin/jfone. At the fame time, beds of fimi-- 
lar quality, but of compofition fomewhat lefs fufible, would. 
enter into: a ftate of vifcidity, fuch as many bodies pafs. 
through in their progrefs towards fufion. In this ftate, the 
particles, though far from poffefling the fame freedom as in a. 
liquid, are fufceptible of cryftalline arrangement *; and the 
fubftance 
* Tus ftate of vifcidity, with its numberlefs modifications, is deferving of. 
great attention, fince it affords a folution of fome of the moft important geologi- 
cal gueftions. The mechanical power exerted by fome iubftances, in the aé of. 
afluming a cryfialline form, is well known. I have feema fet of large and broad 
cryftals 
