282 Geological Remarks on the Lake Regions. 
cies. ‘There is nota single shell in the Strontian deposits of 
Grosse isle—and neither shell nor Strontian in the floor of the 
contiguous river, while the extensive quarries two miles be- 
hind Amherstburgh produce an immense variety of organic 
remains, animal and vegetable, without a vestige of the rare 
erystallizations of Grosse Isle.* 
JOHN J. BIGSBY, M. D:. 
4, os als Remarks on the Lake regions froma letter 
of December 6, 1821, addressed to the Editor by Mapes 
DELAFIELD. 
Professor Buckland’s notice of my present of minerals 
from the North, through your correspondent, is the,only 
knowledge I have of those specimens having been received. 
His analogy concerning the lime stones of certain latitudes; . 
is ead. on a partial view of facts, and is not altogether | 
satisfactory. The transition lime stone appears in “Lake 
Huron, but I had not considered the shell. lime stone to be 
transition. In truth, in the space of sixty miles you. sail . 
from secondary to transition and to primitive formations in 
the north end of Lake Huron. The organic.remains of the 
lime stone of Lake Huron are I believe, peculiar. Ortho- 
ceratites of such size and variety, I have not found described . 
in books. Tribolites are numerous, and partake of the char- 
acteristic of the remains of that region, which is that of prodi- 
gious size. The shores are covered principally. with rolled 
rocks out of place, of very many varieties. Green stone amyg- 
daloids, jasper, and other varieties of trap ; breccia, epidote, 
and others abound. Several of my specimens are pronounced 
to be of volcanic origin, which if true, is the first occurrence 
of such appearances to my knowledge eastof the Mississippi. 
Dr. Bigsby is engaged in the description of the Lake min- 
erals and geology; and has it in his power to.impart much 
information to those who wish to pursue the analogy be- 
tween American and European Geology. I do not doubt 
his exertions will prove of interest and value. ; en 
Perhaps your friend, who forwarded Mr. Buckland’s let- 
ter, would like to know. that the Trilobite is found in she 
Lake Huron lime stone, 
* The mineralogical sketch of Moss Island is to be considered as only my 
personal observations. Ina studied description of that district, I should em- 
body the remarks of Douglass and Bird, 
