geo: 
ffiO'fe-great clisrnges pofterior to the deluge, for %vliich 
the deluge had, how'ever, prepared the fuperficial ftrata 
of the globe: that all thefe changes muft have been ac- 
compliHied chiefly by extraordinary agitations of the 
waters of the ocean, and at the diftance of at leaft three 
thoufand fix hundred years from the prefent time. 
The fourth Effay explains the phenomena of lapidiji^ 
cation. Stones confift of earths conglomerated. A 
lump of any earth of whicli the parts, though cohering, 
are divifible merely by the nail of the finger, is called' 
but indurated earth ; if its cohefion firmly refifi: the action 
of the 'Oail, it is to be denominated Jlcne. Stones are 
hard which cannot be eafily filed, or cut into pieces. 
Thofe are firm which firongly refift perenfiion. Some 
ftones appear to have been formed by cryftaliifation ar¬ 
ranging all their parts, internal and externa!,, in a regu¬ 
lar form. It is effedted from either aqueous or igneous 
folution. All folidifiable matters are fufceptible of 
it. Even thofe filiceous matters, which are now al- 
moft infoluble in water, might be eafily foluble in this 
menftruum in their original fiate of extreme divifion, 
and were probably cryftallifed by depofition from water. 
Nay, in Ipite of whatever Dr. Black and others r.iay 
.have affirmed to the contrary, numerous fadts may be 
produced to ffiow that, even ftill, water may be made 
to take up a certain proportion of tliis earth. Some 
ftones appear to have been formed by the mere concre- 
tion of particles, which, in their primary compofition, 
are probably of different figures, and which therefore 
difplay not in their cohefion the uniform order of cryf- 
tallifation. Other-ftones are formed by the cementation 
of exceedingly fmall nodules, or even of larger ones, by 
the depofition of ftill particles amongft tliem, and the 
cohefion of whole maffes, partly by mechanical force, 
and in part by the reciprocal chemical attradtions of the 
difterent parts. Masiy of the fmaller nodules, which 
are found imbedded in rocks not of the fame nature with 
t'lernfelves, have been formed by an infiltration, in 
which water or fome other fluid carried their particles 
through the fuperficial ftrata, but depofited them after 
penetrating the interior layers only to a certain depth. 
Thofe ftones which we call petrifaBions, have been form¬ 
ed by the gradual fubftitution of ftony particles into 
the places which were occupied by animal or vegetable 
matters that decay while the lapideous depofition takes 
place. Thefe are the difterent modes of lapidification. 
They are exemplified in all the difterent fragments, co¬ 
lumns, and ftrata of rock, which the earth prefents to 
the obfervation of men. 
In the fittli Effay, the difintegratiorif reducing them 
into fands and larger fragments,'is explained, as iiaving 
been often produced by the abforption of water, and by 
itS'congelation or rarefaclion while it was diffufed with- 
in them. The known externa! caufes of the entire de- 
compofition of ftony matters are reprefented to be only 
water, carbon, and carbonic acid gas, which enter into 
new combinations with the faline matters, the fulphur, 
the ferruginous oxyds, the manganefe, the lime, and 
other conftituent parts of the ftones with which they 
come into contact. 
Mountains are the fubjefts of the fixth of thefe Ef- 
fays. The author deferibes the mountains as 
containing v.'ithin them no animal nor vegetable re¬ 
mains I as compofing all the loftieft extremities of the 
earth; as never covering nor leaning upon thofe wliicli 
are called fccondary • as exifting fometimes-in ftrata, but 
oftener in huge rocks ; asvarioully compofed, of granite 
and granitic compounds, gneifs, fchiftofe mica, filice- 
ous Ichiftus, bafanite, jaiper, pitchftone, hornblende, 
hornblende Hate, indurated lithomarga, argillite, trap,- 
ferpentine and potftone, porphyry, honillate, fchiftofe 
porphyry, landftone, rubbk-ltone, farcilite, granular 
limeftone, marlite, gypfum, fluor, and topaz-rock. Of 
each of thefe forts of Itone he gives, in part, the mine- 
jiilogical geography. The Jkondar^ mountains are.next 
>,0 GY.' 41^ 
deferibed, as being eitlier -marigenous oV alinvial; as 
containing in their ftruCture various remains of animals 
and vegetables, terreftrial and aquatic; as always in¬ 
cumbent on primary rocks, or iikelling them ; as ftra- 
tified or columnar, unigenous or polygenous ; as vari- 
oufly compofed of limeftone, fwineftone, oviform lime- 
■flone,. porous limeftone, marlites, and calcareous fand- 
ifones, chalk, gypfuin, argillite, indurated clay, ffiale., 
bituminous Ihale, indurated lithomarga, fiate, argilla¬ 
ceous fandftone, porpliyry, trap, and bafalt; horn¬ 
blende, argillaceous and calcareous breccias, horn- 
ftone, jafper, filiceous breccias, and filiceous fandftone. 
By an ample indudlioii of fadls it is proved, that all 
thefe different forts of ftone have been found in circum- 
ftaiices in which they could not be but of fecondary 
formation. 
In the feventli Effay, Mr. Kirwan deferibes volcanic 
mountains as being generally of a conical forni, of no 
exceedingly ancient origin, burning with no e’xtraordi- 
nary intenfity of internal heat, and not'half fo numerous 
as fome theoretic mineralogifts have fuppofed them to be. 
In the eiglirh Effay, Mr. Kirwan endeavours to ex¬ 
plain the internal arrangement of mountains. _ He here 
relates that their materials are difpofed either in irregu¬ 
lar heaps, or in beds, or ftrata, horizontal, varying from 
that pofition by an angle of from five degrees to forty, 
or fometimes even almofl: vertical. Sometimes the 
ftrata run in the dire6fion of the declivity of the moun¬ 
tains they compofe, and fometimes their courfe is di- 
redlly oppofite to this. Mountains of primitive lime» 
ftone are often in irregular piles, but often,, too,, horir- 
zontally ftratified. Of fecondary calcareous ftrata, the- 
ftrudlure is commonly horizontal. The ftrata of fecon— 
dary mountains, for the moft part, afeend towards the 
primary.—Thefe are fome of the leading truths of this 
curious inveftigation. _ • 
Coal-mines form the fubjeft of the ninth Effay. Pk- 
coal is a compound of bitumen with carbon : its fpecific 
gravity is from i‘23 1*500. The foils within which, 
beds of coal-ufually .occur, are argillaceous, arenilitic, 
trappofe, or calcareous. Thefe are difpofed in ftiata 
over the coal, or in alternation with the ftrata. The 
thicknefs of the ftrata, or learns of coal, varies from 
half an inch even to eighty feet. Shale,, bituminous 
ffiale, or fandftone, are the ftones which generally form 
both the ro^and fioor to/earns oi pit-coal. Sometimes 
thefe feanis are in their dilpofition horizontal. T. hey 
rife at times to angles of from twenty-five degTees to 
forty.five with tlie horizon. It cannot be true, that, as 
has been fuppofed by Genfanne, pit.coal is nothing but 
argillaceous matter impregnated with petrol or afphalt } 
nor that this coal is entirely of vegetable origin noi 
that it is formed from the fat and unttuolity of the ani¬ 
mals of the ocean. The ftrata of this mineral leem ra¬ 
ther to have been formed in conlequence of the difinte- 
gration of many of the primitive mountains by the ho¬ 
mogeneous'union of the petrol and carbon which were 
by that difintegration liberated out of the compofition 
into which they had originally entered.._ Coal is theie- 
fore to be fought, with probability of fucceis, op^y on- 
the fides of primitive mountains, in the viciiiity oi( 
mountains of argillaceous porphyry, amidft fandftone 
and fltale bearing the impreflions of vegetables, 
aUer.ntiting ftrata of limeftone and fandftone, or amidlt. 
ftrata of trap, or whin with fandftone or clay. 
Common fait and its mines are made the i'ubjects 01 
the tenth Effay. The'fea is reprefented as owing us, 
faltnefs to fimple faline I'ubftances held in folution in it 
ever fince the creation. The mines of rock-lalt whicli 
have been in different-places dilcovered, are laid to have 
all originated from the detenfion and evaporation of fea- 
-water. Salt-fprings and lakes arre related to contain and 
pour forth, from time to time, quantities of faline mat¬ 
ter, which, when fubje^ted to calculation, cannot butj- 
by thgir magnitudej excite the greateft aftonifliment. 
Tiicfe 
\ 
