oup extends, is usually
marked by a series of low, gravelly hills, and clayey valleys, on
which a stunted growth of timber prevails, known by the name of 'Oak
Openings.' Small portions of sulphate of strontia, galena, and blende,
with rhomb spar, occur in the upper portion of the group. Gypsum and
salt are, however, the only minerals of economical value: of the
former many thousand tons are excavated. Several acidulous springs
issuing from these deposits, have been found to contain free
sulphuric acid."--_D. D. Owen's Review of the N. Y. Geological
Reports._

Jules Marcou, in his Geology of the United States, places the northern
portion of the southern peninsula of Michigan in the Terrain Devonian.

Report of J. S. Dixon and others, on Grand Traverse Bay, p. 523, in
Michigan Agricultural Reports for 1834, says:

"The atmosphere is moist and wholesome--no disease, and healthy as any
portion of country. It is a well established fact, that water cools
first on the surface, then sinks while the warm water rises, and
consequently ice never forms till the whole body of water has been
cooled to thirty degrees. Now, from this fact, the philosopher will at
once deduce the climate of this region. Traverse Bay is from one
hundred to nine hundred feet deep and the water never cools to
thirty-two degrees till the middle of February, and in Lake Michigan
in the middle never, and so long as the water in these continuous
reservoirs is warmer than the air, the former must obviously warm the
latter.

"It is accordingly well known that in England, on the east side of the
Atlantic 7 deg. or 8 deg. farther north than Traverse Bay, the climate, as it
regards cold in winter, is about equal to that of Washington City,
and so it is on the east side of the Pacific ocean, in Oregon. Hence
it is evident that the seasons on the east side of Lake Michigan must
be uniform.

"Around Traverse Bay the frost seldom kills vegetables till in
November, and seldom occurs in spring later than the 1st of May. In
November it gets cold enough to freeze. The vapors arising from the
lake and bay fall in snow and cover the ground before the frost has
penetrated it at all; it accumulates several months till it is two
feet deep, sometimes deeper, and remains till April; and when it goes
off; cattle find enough to eat in the woods. This region is much more
sunny between the middle of March and December than southern Michigan,
and every vegetable physiologist wi