Physical Geography

Few states show the effects of glaciation as vividly as Wisconsin. The huge continental glaciers of the last Ice Age advanced and retreated several times across most of the state. As the glaciers moved, they ground down hills, gouged out basins for lakes, and deposited vast amounts of debris called drift. Only southwestern Wisconsin escaped the glaciers.

Occupying roughly the northern quarter of Wisconsin is a hilly region known as the Superior Upland. A southern extension of the vast Canadian Shield, it contains many lakes, rivers, and forested hills and ridges. Much of the region lies from 1,000 to 1,700 feet (300 to 520 m) above sea level, with a few hills rising somewhat higher. Southwest of Rhinelander is Timms Hill, which reaches 1,952 feet (595 m) and is the state's highest point. In the far north, the land slopes down to the shores of Lake Superior, whose surface is 600 feet (183 m) above sea level. Offshore are the Apostle Islands, a group of about 20 islands noted for their natural beauty.

South of the Superior Upland, and nearly in the center of the state, is a broad plain that once was the bed of an extensive glacial lake. The plain is the largest expanse of level land in the state.

Southwestern Wisconsin is occupied by the large unglaciated Driftless Area, so called because it lacks the glacial drift found in the rest of Wisconsin and the Middle West. It is rolling to hilly and, in some places, is cut by deep, narrow river valleys. The area is higher than the surrounding land and a number of hills reach elevations of 1,200 to 1,700 feet (370 to 520 m). On the west, steep bluffs drop sharply into the valley of the Mississippi River.

In eastern and southeastern Wisconsin is a glaciated area of ridges and hills, with little level land except near the shores of Lake Michigan and Green Bay. Nearly everywhere, the land is dotted with glacial remnants such as lakes, elongated hills known as drumlins, and ridges called moraines and eskers. Especially prominent is the Kettle Moraine stretching from near Beloit northeastward toward Sheboygan. Another long ridge forms the spine of the Door County peninsula.

Most of the larger rivers begin in the Superior Upland and flow toward the Mississippi River, which forms much of the state's western border. From north to south, the largest streams include the St. Croix, Chippewa, Black, Wisconsin, and Rock. Northwest of Madison, the Wisconsin River has cut its way through deep sandstone to form the scenic Wisconsin Dells. Of the rivers that drain to Lake Michigan, only the Fox, Peshtigo, and Menominee are notable. The Fox River, joined by its chief tributary, the Wolf, flows through Lake Winnebago and eventually reaches Green Bay. The Menominee forms part of the border with Michigan.

An estimated 9,000 lakes dot Wisconsin, mostly in glaciated regions. Lakes are especially numerous in the Superior Upland, where there is a thriving resort and recreational industry. Largest of the northern lakes are Chippewa, Flambeau Flowage (created by a dam on the Flambeau River), and Lac Court Oreilles. In the east and south are other large lakes, including Lake Winnebago—the state's largest lake. On the shores of Lakes Mendota and Monona is the state capital, Madison.

Wisconsin has a continental climate similar to that of other northern states lying east of the Dakotas. Winters are long and severe, especially in the north and central areas, where temperatures occasionally drop to -40° F. (-40° C.). Average January daily highs and lows in the north are about 20° and 5° F. (-7° and -15° C.); in the south, about 25° and 10° F. (-4° and -12° C.). Summers throughout the state are warm to hot, particularly in the south. Even in the far north, there are usually several days of hot weather each summer. Occasional summer cold spells, however, can drop temperatures below freezing as far south as central Wisconsin. July daily highs and lows are approximately 80° and 55° F. (27° and 13° C.) in the north; 85° and 60° F. (29° and 16° C.) in the south. Lakes Michigan and Superior moderate the climate only within a short distance of their shores.

Annual precipitation, including rain and snow, averages 30 to 35 inches (760 to 890 mm) in north-central Wisconsin and about 25 to 30 inches (640 to 760 mm) everywhere else. About two-thirds of the yearly total occurs during the warmer months. Snowfall ranges from about 30 inches (760 mm) in the south each winter to more than 60 inches (1,520 mm) in most of the north. On the slopes of the Gogebic Range, in the extreme north, annual snowfall often totals more than 100 inches (2,540 mm). Throughout the state, low winter temperatures keep snow on the ground for many weeks at a time.

Natural Vegetation.

In the early 1800's, when rapid settlement began, forests covered about 85 per cent of Wisconsin. Great stands of white pine and other evergreens, mixed with hardwoods such as birch, maple, and oak, occupied much of the land. Prairies dotted parts of the south, and marshes were scattered throughout lowland areas. By the early 20th century, excessive cutting and fires had reduced the forests to barely half their original extent. The present forests are nearly all second-growth, with aspen having replaced much of the original northern pine. Once considered a nuisance, aspen is now a valuable source of pulp. Other predominant trees include pine, birch, oak, maple, and basswood.