308. Notice of the Peninsula of Michigan. 
a 
and sienite on parts of the shore of lake St. Clair, and rolled 
stones in Oakland and other counties. But of rocks in situ, 
few sections of our country are so destitute of accessible beds 
_for economical purposes ; though there are indications that 
many districts of the peninsula, where no rocks appear, have 
a calcareous basis. Sinks which are rarely observed except 
in limestone countries, are often seen in the undulating inte- 
rior, Springs are there found copiously depositing calcere- 
ous tufa. Extensive beds of limestone occur in lakes Michi- 
gan, Huron, and St. Clair, and there are calcareous rocks in 
place, in the St. Joseph, Grand river, and other streams of 
the western declivity. Limesione and sandstone ledges are 
located in the north-western part of the peninsula, on the 
shores of lake Huron and the banks of Flint river, where 
slate embracing considerable sulphur, and indications of coal 
ee Coal has been discovered on another branch of the 
aganaw. 
~ A considerable part of lake St. Clair is reported to have a 
limestone bed, often covered by a thin stratum of sand. ‘The 
connecting streams, St. Clair and Detroit, contain limestone 
‘rocks in situ. From an island situated inthe latter river, 
eighteen miles below Detroit, large supplies of excellent 
building stone are quarried. [tis secondary, compact, light 
coloured limestone, is easily wrought, and is a good material 
for lime. Fine specimens of f carbonate [suphate 2? Ed.] of 
strontian have been found on this island. 
Large beds of limestone containing petrifactions of marine 
shells, occur on the river Rouse, commencing about fifteen 
miles from its termination in lake Erie. Most of the nume- 
rous islands in the western part of lake Erie, are based on 
secondary limestone, and bordered hy ledges of that mine- 
ral. 
In extensive tracts of the north-western part of the adja- 
cent state of Ohio, the soil rests on limestone. Beds of that 
rock have been frequently noticed in the northern part of In- 
diana. ‘They are generally covered by clay. 
Argillaceous oxide of iron exists in many parts of the 
territory, but has not been found in large beds. Yellow 
ochre and chalybeate springs are common. Saline waters 
have been a ed in several districts, but do not hold in 
solution a profitable quantity of muriate of soda. It is proba- 
ble that richer ay ings may be obtained by boring. In Mon- 
roe county there is a very strong and copious sulphur spring. 
