cks. Since the nearest beds of primitive rocks
first appear in Minnesota and the northern part of Wisconsin, their
presence here can be accounted for only by assuming that at the time
this region was covered with water they were floated down from the
North, enclosed and supported in masses of ice, which, melting, allowed
the rocks to sink to the bottom. A still further proof of the presence
of the ocean here in former times is to be found in the sea-shells which
occur upon many of the higher knolls and bluffs west of the Mississippi
in Iowa.

Illinois contains probably more coal than any other State in the Union.
It is mined at a small depth below the surface, and crops out upon the
banks of most of the streams in the middle of the State. These mines
have been very imperfectly worked till within a few years; but it is
found, that, as the work goes deeper, the quality of the coal improves,
and in some of the later excavations is equal to the best coals of Ohio
and Pennsylvania, and will undoubtedly prove a source of immense wealth
to the State.

The two northwestern counties of the State form a part of the richest
and most extensive lead region in the world. During the year 1855, the
product of these mines, shipped from the single port of Galena, was
430,365 pigs of lead, worth $1,732,219.02.

Copper has been found in large quantities in the northern counties, and
also in the southern portion of the State. Some of the zinc ores are
found in great quantities at the lead mines near Galena, but have not
yet been utilized. Silver has been found in St. Clair County, whence
Silver Creek has derived its name. It is said that in early times the
French sunk a shaft here, from which they obtained large quantities of
the metal. Iron is found in many parts of the State, and the ores have
been worked to considerable extent.

Among other valuable mineral products may be mentioned porcelain and
potter's clay, fire clay, fuller's earth, limestone of many varieties,
sandstone, marble, and salt springs.

* * * * *

Illinois has an average temperature, which, if compared with that of
Europe, corresponds to that of Middle Germany; its winters are more
severe than those of Copenhagen, and its summers as warm as those of
Milan or Palermo. Compared with other States of the Union, Northern
Illinois possesses a temperature similar to that of Southern New York,
while the temperature of Southern Illinois will