Mineralogy, Geology, &c- 37 
are somewhat higher. | Here the water glides down pretty 
rapidly over a bed of solid limestone. From the appear- 
ance at this place, and from various other reasons which I 
e not now time to state, | have no doubt but at some 
pees period of time this northern extremity of Lake Erie 
was entire, and the waters of this and the “ge lakes emp- 
tied epeeely yes through a southern channe' 
3. New Locality of Chrysoberyl. 
Saratoga Springs, July 29, 1821, 
TO Fear aESER ee 
Dear Sir, 
~ kag Ma Fae pee = Sg tiagin a wot whe a me io en gt aes ae ee et 
<ike oe nce Pee ye ae ae pres RS, ee of ee =e 
= i 
Prismatic Mica, presum ing ts as these 
minerals Gave not oecurred very frequently in the U. States, 
it may afford you some gratification. They are found in a vein 
of granite which passes through gneiss; the vein was dis- 
covered some years ago, and fine specimens of laminated 
mica and common schorl, (black tourmaline) which occur 
in great abundance, and sometimes in beautiful, (though 
high-rock springs at Saratoga, and nnd forms" a part of the’ im- 
itive region which approaches us from the north, and ter- 
een or passes beneath the secondary, near this’ iis 
The surface of this rock is somewhat elevated, mie remains 
uncovered for the distance of from two to three hundred 
his vein, 
Ist. Felspar,—this assumes more or less the crystaline 
form, aa aifords well defined crystals of adularia. 
the mass of its gangue. The colour is 2 shining velvet 
black. Itis perfectly opaque. 
