GY P's UM. 
found in this mafs of ¢ypfum, the determination of the 
fpecies to which they belong, &c. very interefting memoirs 
have been given ~ 4 Cuvier, in the Annales du Mufeum 
ad’ Hiftoire Nature 
. Buta ee on which great ftrefs is laid by 
a Cuvier and Brongniart, is, that in the gypfeous 
ueftion frefh-water fhells have been difcovered. Thefe 
rw been piiested < 
namely, that the gypfum of Mont- 
martre, and of other iheales of the bafin of Paris, have origi- 
nated by cryttallization in frefh-water lakes. Another effen- 
tial character of this Ppbeaaeer mafs of gypfum, is the pre- 
fence of bariarege of mammiferous animals, no traces of 
which have been difcovered in ‘ae lower mafles. 
On a uppermott mafs of gypfum re% ftrong ftrata, both 
ef calcareous an argillaceous marle. It is in the lowermoft 
of thefe beds, in a white, friable, 
peared in a horizontal po- 
fition, Inthe fame Serie’ of ftrata (but only at Romain- 
ville) have been found fhells belonging to the genera of G 
lymaea and planorbis, and thefe appear not to differ in 
any from the fpecies ftill exilting in the marfhes of 
France. This appears to prove é that thefe marles, as well as 
the fot on which a reft, are the produétions of frefh 
ear 4 ace ite marles are is a great number 
face, con seas of earthy fiiphare of trom anid; 
a iia above, a thin layer, or d telline, 
are found. No folfis are dif- 
s and en ae of 
us 
1 ve beds of marle 
fucceed the green clays are thick, nor do ey 
to contain “ foffils ; See thefe Beds are imme 
la 
nen remai f thel he pr es of which 
rir eee the genera cerites, a tins fe us, 
cardium, &c. Alfo fragments of the palate of a ray ana- 
are found Il the 
“or 
us bed othe 
of gypfum in the sy nota of Paris, The authors 
the memoir, of which the above is extracted, were inclined 
divide pee into two, and to feparate the hiftory of the mar 
marles of the top from thofe of the frefh-water marleta 
gypfum at the bottom ; but the {trata are fo fimilar to ez 
r, and accompany "each other fo conftantly, that th 
preferred merely to point out this divifion, without rea 
making it. ‘The principal differences profented by 
hillocks that belong to the gypfum formation of Paris, accord- 
ae HELE 
= 
leagues. It appear ‘. that in this zone it is only ‘ee 
nences of the centre which exhibit inane ce > mafles 
of gypfum ; oe of the edges, fuch as the plafter-q varie 
Clamart, Bagneaux, Antoni, Mont-Valerian, tae 
thofe of the as, fuch as e platter-quarries of Chale 
and Triel, fhew a 
ingle mafs only. ‘This mafs feems to be 
analogous to that which the workmen call the firft, (namely, 
the moft fuperficial,) siaegt 3 chara@eriftic 
mains of cecahe ere are fou and becaufe its marles 
are Saag: thofe bese and humerous = ad cryftals of 
fum which are obferved in the m of the fecond and 
tee third mafs. Sometimes the ooihed above are almoft 
entirely wanting; fometimes the gypfum itfelf is ge 
» or r reduced to a thin bed. In he a ie 
fils n r St Cyr; thofe o Virobay are in 
predicainet 3; thofe of Meudon, of Ville pric are ae 
the latter. From all that has been faid, it appears, 
the formation of gypfum, of the environs of Paris, is a 
depolition ee ee 
pane chemical chara&er of spe! is, generally panei 
he fame in ali the fub-fpecies. 
When iS ee re 
lofes 1 its water of cryftalli eee e hick Te rbs water 
into a white powder ‘(termed titer), is bet 
- come Sard. dy is almoft infufible 
pears to rgo part vitrification 
intenfe beat of the Sue ipe. — are “told 4 ae 
that to effeét this para BT is Patent to nad of aig 
of | in the direétio: 
comes a fecond ier thick vt ted but fubdivided tae 
dakota - 
ee a 
more or tele tices o seh vena which: ie Without! ‘ne 
Such are the ftrata that generally ‘compole the formation 
