II.

Physical Geography

Indiana ranks 38th among the states in size, with a total area of 94,322 sq km (36,418 sq mi), including 818 sq km (316 sq mi) of inland water and 609 sq km (235 sq mi) of Lake Michigan over which it has jurisdiction. Indiana is roughly rectangular in shape, and the state has a maximum dimension north to south of 459 km (285 mi) and a maximum east to west dimension of 285 km (177 mi). The state is bordered on the north by Lake Michigan and the state of Michigan, on the east by Ohio, and on the west by Illinois. The Ohio River separates Indiana from Kentucky on the southern border.

A.

Natural Regions

Indiana includes parts of two natural regions, or physiographic provinces, of the United States, the Central Lowland and the Interior Low Plateau. Both regions form part of a larger natural region, the Interior Plains. Indiana lies mainly between 150 and 300 m (500 and 1,000 ft) above sea level and has an average elevation of about 210 m (700 ft). The highest point, in Wayne County near the Ohio state line, is only 383 m (1,257 ft) above sea level.

The Central Lowland, in Indiana, is a generally flat area that covers the northern and central portions of the state. Much of its appearance is a result of glacial action that occurred during the Ice Age, which ended about 10,000 years ago. During that period several great ice sheets advanced from the north and retreated across Indiana. Early ice sheets covered all of Indiana except a hilly irregular wedge roughly south of a line connecting the cities of Evansville, Bloomington, and New Albany. Later ice sheets covered only the northern and central sections of the Central Lowland. The ice sheets left a deep layer of glacial drift that has weathered into soils made up of sand and clays intermingled with gravel. This type of glacial drift is termed till, or ground moraines.

Occasional areas of boulders and rough stones were deposited in terminal or lateral moraines, now rising in low, deeply eroded hills marking the edges of the glacier’s path. As the glaciers melted, they left deposits of sand and gravel washed out by meltwater streams. These deposits form a natural conduit for groundwater and are the source of well water in large parts of the state.

The most recently glaciated areas, limited to northern Indiana, are covered with large areas of infertile sandy deposits and numerous swamps and marshes. When drained, the swamps and marshes provide fertile muck soils. Low sandy ridges and hills of glacial drift are common in this section of the Central Lowland. Central Indiana, which has a generally less varied relief, includes the flattest areas in the state and also some of the most fertile soils. The very flat and fertile lands of west-central Indiana form an extension of the Grand Prairie area in Illinois. Only in some east-central areas do concentric bands of low sandy ridges add greater diversity of relief. Glaciated areas in southern Indiana, covered very early in the Ice Age, have been exposed longer to the forces of erosion than have the areas farther north. As a result, the landscape in even the glaciated areas of southern Indiana is characterized by numerous rolling hills and valleys.

The Interior Low Plateau, in southern Indiana, is a hilly area that was never glaciated by the ice sheets. Long subjected to erosion, it is an area of sharp ridges, deep gorges and scenic waterfalls. There are also numerous caves and sinkholes, which have been formed in places where water action has dissolved the underlying limestone of the plateau. Wyandotte Cave and Marengo Cave, about 50 km (about 30 m) west of New Albany, are two of the largest caves. Limestone bedrock exposed in the unglaciated areas provides the state with a major building stone, Indiana limestone. One of the world’s leading exposures of Devonian Period limestone fossils is in the Falls of the Ohio State Park in New Albany.

B.

Rivers and Lakes

Most of Indiana’s rivers flow southward and westward and form part of the Mississippi River system. In addition, there are several small rivers that flow northward to Lake Michigan or eastward, through Ohio, to Lake Erie. The watershed, or dividing line, in Northern Indiana between the Mississippi River system and the Great Lakes drainage basin is generally low, swampy, and poorly defined.

The Ohio River, a major tributary of the Mississippi River, forms a navigable route along the entire length of the Indiana-Kentucky state line. The Ohio’s major tributary in Indiana is the Wabash River. The Wabash, 824 km (512 mi) in length, flows generally westward across north central Indiana and then turns southward to form a lengthy section of the Indiana-Illinois state line. In Indiana the principal tributaries of the Wabash are the Tippecanoe River in the north, and the East Fork and the West Fork of the White River, which drain large areas of the southern and south central portions of Indiana. Indianapolis, the capital, is located on the West Fork of the White River.

The major river in northwestern Indiana is the Kankakee River. The Kankakee rises near South Bend and flows westward across Indiana into Illinois, where it joins the Des Plaines River to form the Illinois River, a tributary of the Mississippi. In northeastern Indiana the Maumee River, which drains to Lake Erie is formed at Fort Wayne by the junction of the Saint Marys and Saint Joseph rivers. There is another Saint Joseph River, which loops through South Bend in northern Indiana to enter Lake Michigan in Michigan.

There are about 1,000 small natural lakes in Indiana, chiefly in the northern part of the state. The largest is Lake Wawasee, which covers almost 13 sq km (5 sq mi). In the central part of the state there are several lakes that were created behind dams on a number of smaller streams. They include Monroe Lake, near Bloomington; Geist and Eagle Creek reservoirs, northeast and northwest of Indianapolis; and Mississinewa and Huntington reservoirs, north of Marion.

C.

Climate

Most of Indiana has a humid continental climate, with cool winters and long, warm summers. The extreme southern part of the state is within the humid subtropical climate zone and has somewhat warmer temperatures and receives more precipitation.

C.1.

Temperature

Throughout the year, temperatures do not vary greatly from place to place but are generally a few degrees higher in southern Indiana than in northern Indiana. Average July temperatures in all of the state are in the lower to mid 20°s C (mid 70°s F) and range from 23° C (74° F) in the north to more than 26° C (78° F) in the south. July temperatures in Indianapolis average a high of 30° C (86° F) and a low of 18° C (65° F). In summer, daytime highs in Indiana often rise to the upper 30°s C (lower 100°s F), and on occasion they may reach into the lower 40°s C (lower 110°s F).

Average January temperatures range from -3° C (26° F) in the north to more than 1° C (34° F) in the Ohio River valley. January temperatures in Indianapolis average a high of 1° C (34° F) and a low of -8° C (17° F). In winter, freezing weather occurs throughout the state, and lows in the lower -30°s C (lower -20°s F) are sometimes recorded in northern Indiana.

C.2.

Precipitation

Precipitation (rainfall and snowfall) ranges from less than 860 mm (34 in) a year in the northwest to more than 1,170 mm (46 in) in the hills of southern Indiana, near the Ohio River valley. Precipitation is distributed throughout the year although in the north the heaviest rainfall comes between April and July. Hailstorms are common in the north and occur occasionally in the south during summer and cause damage to crops. Tornadoes associated with frontal storms can occur, and occasionally do considerable damage. In winter heavy snowfalls are common in the north and occur occasionally in the south.

C.3.

Growing Season

The growing season, or period between the last killing frost in spring and the first killing frost in the fall, increases from less than 150 days in the northeast and along the Kankakee River to more than 190 days in the southwest. The last killing frost in the spring usually occurs in mid-April in the south and as much as three weeks later in parts of the Kankakee River valley. The first killing frost in the fall occurs first in northern Indiana, where it can usually be expected in the second two weeks of October. However, the waters of Lake Michigan retain their warmth into the fall and sometimes delay killing frosts along the lakeshore for several weeks.

D.

Soils

The most productive soils in Indiana are in the most recently glaciated prairie areas of the west central parts of the state. Deep and well-drained, these prairie soils, like those of the Grand Prairie in adjoining Illinois, are exceedingly fertile and intensively farmed. North of the prairie soils are found muck soils, which occur in swamp areas and are fertile when drained. Gray-brown forest soils cover the remainder of northern and central Indiana and also an extensive area of the hill lands in the southern part of the state. Where the land is flat or gently rolling, as in most of central Indiana, the gray-brown forest soils, somewhat acidic, are only slightly less productive than the prairie soils. However, where the soils have been longer subject to leaching of minerals, as in the lighter colored forest or prairie soils of the older glaciated areas of the south, or to severe erosion, as in the unglaciated areas, the soils are lower in fertility. In the rainy southern areas the soils tend to have a hard pan, or impervious soil layer just below the surface that impedes natural drainage of the land. Crops can be grown on such soils, but the yields per acre are lower than in most other areas of Indiana, and many farmers choose to keep their land in pasture. In much of southern Indiana the soils best suited to farming are the alluvial soils found in river valleys.

E.

Plant Life

Before the land was cleared for settlement in the 18th and 19th centuries, forests covered more than four-fifths of Indiana. The forests were mainly deciduous. Grasslands areas occurred in places between the forested areas and were most extensive in far western Indiana.

Forests and woodlands cover 20 percent of Indiana. Much of the forested land is now contained in state forests and Hoosier National Forest. The principal forested areas are in the south. There are small forested areas in the north, along the shores of Lake Michigan, and elsewhere along the watercourses. Numerous species of deciduous hardwood trees grow in the state. Among the most common are black walnut; American sycamore; beech; the tulip tree, or tulip poplar, which is the state tree; and several species of oak, poplar, hickory, and maple. Other trees found in much of the state include the eastern red cedar, honey locust, flowering dogwood, eastern cottonwood, aspen, and species of elm and ash. Among the trees in the southern counties are the common persimmon, sweet gum, bald cypress, eastern hemlock, yellow buckeye, and river birch. In the north are found the tamarack and the yellow birch. In the lakeshore area known as the Indiana Dunes, and in some hilly, forested areas of southern Indiana, are found the jack pine and the white pine.

The Indiana Dunes region, much of it within Indiana Dunes State Park, forms an unusual natural habitat. It is characterized by high, tree-covered sand dunes, long stretches of beaches, and numerous marshes. A great variety of trees and other plants grows there within a very small area. Some of the plants and trees are native to widely different environments. They include the prickly pear cactus, oaks and beeches common in the eastern United States, and the lichen mosses and bearberry of the Arctic, as well as luxurious ferns and more than 20 varieties of orchids.

Wildflowers found in Indiana include the violet, wild lupine, wood anemone, oxeye daisy, goldenrod, wild carrot, aster, gentian, and sunflower. The flowering shrubs found throughout the state include the elderberry, bittersweet, sumac, and wild rose. Among the other plants that grow in Indiana are the wild peppermint as well as the insectivorous pitcher plant and species of sundew. Wild cranberries and blueberries are present in a few remaining undrained swamp areas, where bladderwort, water-milfoil, and similar plants are also found.

F.

Animal Life

Bison, or American buffalo, once inhabited Indiana, but all had disappeared by the time of extensive settlement in the Indiana region in the early 19th century. The black bear, wildcat, and timber wolf, common in the 19th century, are also no longer found in the state. The red fox and the white-tailed deer are still to be found, however. Among the smaller mammals that are common in Indiana are the muskrat, mink, chipmunk, opossum, gray squirrel, raccoon, cottontail, striped gopher, and woodchuck.

An estimated 200 species of birds appear regularly each year in Indiana, although nearly 400 species have been recorded there. Large numbers of birds pass through the state during the spring and fall migrations. The migratory routes cross the northwestern and southern sections of the state, which lie in the so-called Mississippi Flyway. Migratory birds include species of herons, sandpipers, warblers, blackbirds, sparrows, swallows, thrushes, rails, and flycatchers. Migratory waterfowl that are also game birds include the Canada goose, coot, and blue-winged teal and the mallard, black duck, and other kinds of ducks. One of the state’s principal game birds is the bobwhite, a species of quail, which is a year-round resident. Other resident game birds are the ring-necked pheasant, prairie chicken, and ruffed grouse. Among the great variety of other resident birds in the state are the rock dove, common crow, herring gull, turkey vulture, killdeer, blue jay, black-capped chickadee, eastern meadowlark, western meadowlark, white-breasted nuthatch, several kinds of hawks, owls, and woodpeckers, and the cardinal, which is the state bird.

The Indiana Dunes are visited by a great variety of birds that nest or stop over there during migration. Among those not frequently seen elsewhere in Indiana are the long-tailed jaeger, bald eagle, sandhill crane, western grebe, and Bewick’s wren.

Fish in the rivers and lakes of Indiana include the carp, catfish, freshwater drum, gizzard shad, bowfin (or dogfish), smallmouth bass, largemouth black bass, bluegill, and species of sucker, sunfish, and gar.

G.

Conservation

The Indiana department of environmental management is responsible for air pollution control, water pollution control, and management of solid waste and hazardous waste. The state department of health has some responsibilities for drinking water. Most natural resource operations are under the state department of natural resources. In 2006 the state had 29 hazardous waste sites on a national priority list for cleanup due to their severity or proximity to people. Between 1995 and 2000, the amount of toxic chemicals discharged into the environment increased by 19 percent.

G.1.

Air Quality

The quality of Indiana’s air is good in most rural areas, but it is fair to poor in the industrialized northwest, where soot and dust (particulates) are the primary problem, and along the Wabash and Ohio Rivers, where sulfur dioxide from power plants is the chief problem. Most urban areas have high atmospheric pollution levels, owing to motor vehicle emissions.

G.2.

Waste Management

Indiana has a solid waste (trash) disposal program, a hazardous waste program, and a program to prevent leaks from underground storage tanks, located primarily at fuel stations. Most of Indiana’s trash is dumped in landfills. Laws enacted in the early 1990s require that new landfill construction follow strict guidelines to prevent seepage. The laws also restrict the growing inflow of waste from other states and encourage Indiana’s efforts in trash recycling.

G.3.

Water Quality

Groundwater is the source of drinking water for almost one-third of the state’s population. Indiana’s groundwater contains limited synthetic organic chemicals, nitrates, brine and salt, and pesticides, common in agricultural states. All municipal water supplies are treated to ensure water quality. In 1985 the state legislature set up a loan fund to enable local communities to construct or expand sewage treatment plants. The measure has helped to prevent further deterioration of the streams.