SCIENCE.

CONDUCTED BY CHARLES R. DRYER.

"By science I understand organized knowledge, working by method, based on evidence, and issuing in the discovery of law.-E. A. SONNENSCHEIN.

consist of a series of shales, sandstones and limestones laid down upon the bed of a shallow ocean off the shore of a land area which lay to the eastward. These strata are shown by borings to be more than 3,000 feet thick. They have never been compressed, folded, or violently disturbed; but have been gently lifted into a very flat arch, the crest of which extends from Union county to Lake county. From the crest of the arch the strata

THE GENERAL GEOGRAPHY OF INDIANA.

CHARLES R. DRYER.

POSITION AND BOUNDARY.

Indiana is one of the North Central states, situated in what is sometimes called the Middle West, between the upper Great Lakes and the Ohio, and mostly in the Mississippi basin. The central parallel of the United States, the 39th, crosses its southern third and it is included between 37° 41′ and 41° 46′ north latitude, and between 84° 44′ and 88° 6′ west longitude. It is bounded on the north by the parallel which is ten miles north of

slope in the latter direction being about twenty feet to the mile.* The oldest rocks exposed are the Hudson river shales, in the southeast; the youngest are the Carboniferous, along the west side. PHYSICAL HISTORY.

Indiana has been a land surface since the close of the coal period. Subjected during those millions of years to weather and stream erosion, it was maturely dissected into a complex network of valleys, inter-stream ridges, and isolated buttes. Over this surface the great Laurentide glacier repeatedly passed, extending once as far as the glacial boundary shown on the map, and again to the "Wisconsin" boundary. Its effect was to

east by the meridian of the mouth of the Great Miami river; on the south by the Ohio; and on the west by the Wabash river and the meridian of Vincennes. Its extreme length is 250 miles, its average width 145 miles, its area 36,350 square miles.

ELEVATION.

According to Powell's division of the United States into physiographic regions, Indiana lies mostly on the Ice Plains, but includes a small portion of the Lake Plains on the north, and of the Alleghany Plateau on the southeast. The highest land in the state, in southern Randolph county, is 1,285 feet above tide; the lowest, at the southwest corner, is 313 feet. The area above 1,000 feet comprises 2,850 square miles in three tracts: (1) an irregular area around the headwaters of the Whitewater river in Union, Wayne, Randolph, Delaware, Henry, Rush, Decatur, Franklin and Ripley counties; (2) a narrow, crescentic ridge in Brown county; (3) a considerable area in Steuben, DeKalb, Noble and LaGrange counties. Isolated peaks rise in Brown county to 1,172 feet, and in Steuben to 1,200 feet. The area between 500 and, 1,000 feet in elevation is 28,800 square miles, and that below 500 feet is 4,700 square miles. The average elevation of the state is 700 feet.

GEOLOGICAL STRUCTURE.

The rocks of Indiana are all sedimentary and National Geographic Monographs, No. 3.

valleys, and to leave the surface plastered over with a great mass of loose material, much of which was brought from northern regions. Since the final disappearance of the ice the streams have partially cleared out a few of the old valleys and have begun to cut a system of new ones in the surface of the drift, but this cycle of erosion is still in its infancy. Thus, the greater part of Indiana is a plain of glacial accumulation, of very recent origin, and too young to have developed more than rudimentary features.

PHYSIOGRAPHIC REGIONS.

The most striking physical contrast in Indiana is that between the glaciated and unglaciated areas. A comparison of the topographic map with that showing the revised glacial boundary brings out this contrast sharply. North of the limit of drift the contour lines; run in large curves and are far

*See the excellent sections of Professor Cubberly, showing the structural features of Indiana, in 18th Report of State Geologist, p. 219.

thee INLAND EDUCATOR, Vol. III., p. 25.

Contour lines are lines of equal elevation which run across the country, each everywhere at the same height above the sea. The shore of the ocean is the basal contour line, and if the sea level should rise a hundred feet it would mark a new contour line at that level. Where contour lines are far apart the slopes are gentle and the surface comparatively smooth; where they are close together the slopes are steep and the surface rough and broken. The contour lines on the topographic map of Indiana are general and approximate only. Fuller and more accurate surveys are necessary before they can be drawn with exactness and detail.

apart, showing the general smoothness and monotony of the surface. South of the glacial boundary the lines are crowded and extremely tortuous, showing a surface much cut up. The limit of drift encloses and fits this area of broken surface as a man's coat fits his shoulders.

The Ohio Slope.-That portion of the state which slopes directly to the Ohio, including the driftless area and the southeastern part of the drift plain, is a region of deep, narrow valleys, bounded by precipitous bluffs, and separated by sharp, irregular divides. Isolated knobs and buttes are numerous; the crests and summits are from 300 to 500 feet above the valley bottoms. The streams are rapid and broken by frequent cataracts. All open out into the Ohio Valley, a trench from one to six miles wide, 400 feet deep and bounded by steep

bluffs.

The Central Plain.-North of an irregular line extending in a general direction from Richmond to Terre Haute, and south of the westward flowing portion of the Wabash from Fort Wayne to Attica, the topography is that of an almost featureless drift plain. It is traversed by numerous morainic ridges, but they are low and inconspicuous. The traveler may ride upon the railway train for hours without seeing a greater elevation than a hay stack or a pile of saw dust. The divides are flat and sometimes swampy, the streams muddy and sluggish. The valleys begin on the uplands, as scarcely perceptible grooves in the compact boulder clay, widen much more rapidly than they deepen, and seldom reach down to the rock floor.

The Northern Plain.-The portion of the drift plain north of the Wabash river is more varied than the Central Plain, and comprises several regions which differ materially in character. A small area around the head of Lake Michigan is occupied by sand ridges and dunes, partly due to a former extension of the lake and partly to present wind action. Some of the drifting dunes are more than 100 feet high. This region is separated by a belt of morainic hills from the basin of the Kankakee, which contains the most extensive marshes and prairies in the state. This region also is traversed by numerous low ridges of sand, the origin and character of which are not yet well understood. Many of its features are probably due to the fact that during the retreat of the ice-sheet it

was temporarily occupied by a glacial lake, which

received the wash from the high moraines to the eastward. Northeastern Indiana is the region of high moraines, and has a strongly marked character of its own. A massive ridge of drift, twenty-five miles wide, 100 miles long, and from 200-500 feet thick, extends from Steuben county to Cass county and is joined by several smaller branches from the

Northwest. This is the joint moraine of the Erie and Saginaw lobes of the Laurentide glacier. Much of its surface is extremely irregular, presenting a succession of rounded domes, conical peaks, and winding ridges, with hollows of corresponding shape between, which are occupied by innumerable lakes and marshes; the highest points are 100-300 feet above the level intermorainic intervals. A large proportion of the material is sand and gravel. A small area in eastern Allen county is a part of the bed of the glacial Maumee Lake. DRAINAGE.

The general slope of Indiana is to the southwest, as indicated by the course of the Wabash river and its tributaries, which drain two-thirds of the state. Of the remaining third, one-half is drained

directly to the Ohio and one-half to Lakes Erie and Michigan, and to the Mississippi through the Illinois.

The

The Wabash River is the great artery of Indiana, which it traverses for more than 400 miles. fall is quite uniformly about eighteen inches per mile. Its current is gentle and unbroken by notable rapids or falls. Its valley is quite varied in character. Above Huntington it is a young valley, without bluffs, terraces or flood plain. Below Huntington, it once carried the drainage of the upper Maumee basin, and is nowhere less than a mile wide as far down as Attica. Below

that point its width varies from two to six miles. The original valley has been largely filled with drift, which the present river has been unable to clear out. It winds between extensive terraces of gravel, which border it at various elevations, and flows at a level from fifty to one hundred feet above the original rock floor. Below Terre Haute, the wide flood plain, ox-bow bends and bayous give it a character similar to that of the lower Mississippi. The upper tributaries as far down as Lafayette are post-glacial streams in drift valleys, whose courses are largely determined by the trend of the moraines. Below that point the smaller tributaries enter the river through picturesque sandstone gorges."

White River, the largest tributary of the Wabash and rivaling it in volume of discharge, is a much more varied and complex stream. The larger West Fork rises at the summit level of the state in Randolph county. In its upper course it is moraine

*Note on the Wabash River.-The outline for Township Institute Work for 1896-7 called for an essay on the Wabash river, and several thousand teachers discovered that very little is known about the Wabash, and that little is so scattered as to be unavailable. It would be much easier to learn the facts about the Nile, Ganges or Danube. Any one who will make a careful study of any portion of the Wabash and contribute a report, with maps, to the public press will make a valuable

addition to geographic science.

guided, like the upper tributaries of the Wabash, and presents the same characters as the other streams of the central plain. In Morgan county it assumes a different aspect, and thence to its mouth flows through a valley from one to three miles wide, 100 to 300 feet deep, bordered by wide bottoms. The East Fork rises on the same elevation as the West, but reaches its destination by a more tortuous course. Although its length is increased and its slope decreased by its numerous meanders, it is still a swift stream. Both forks of White river suffered many disturbances during the glacial period, which have not yet been studied in detail, but are obvious from the varying character of their valleys and from the terraces which border them at all heights up to 300 feet.

The Whitewater River, takes the shortest course of all from the summit level to the Ohio, and its average fall is about seven feet to the mile. At Richmond it has cut a narrow gorge into the soft shales 100 feet deep. In strongest contrast with this and the other rivers of the Ohio slope is the Kankakee, which winds through wide marshes with a scarcely perceptible current, and without definite banks. Its basin, however, is sufficiently elevated to render good drainage possible by the construction of the requisite ditches, and much has already been done to that end.

PHYSIOGRAPHIC FEATURES.

Many important land forms are wanting in Indiana. There are no mountains, no valleys formed by upheaval or subsidence, no volcanoes or volcanic rocks except foreign fragments brought by the ice-sheet, no features due to disturbance of the earth crust except the rock foundations of the state itself.

Plains. As already indicated, the greater part of Indiana is a plain of accumulation; the surface of a sheet of glacial drift which varies in thickness from a few feet to 500 or more. The average thickness is more than 100 feet. It consists chiefly of a mass of clay containing more or less gravel or boulders-the till or boulder clay of the geologists. This is locally varied by heaps, ridges, sheets and pockets of sand and gravel, and in the southern part of the state is overlain by a peculiar fine silt called loess. The boulder clay is the grist of the glacial mill, and is composed of a very intimate and heterogeneous mixture of native and foreign materials, containing fragments of almost every known mineral and rock. The large fragments, or boulders, are widely distributed, and of every size up to thirty feet in diameter. They are nearly all igneous or metamorphic in character and can be traced back to their origin in the Canadian highlands north of the Great Lakes.

by the removal of the original rock surface to an unknown depth, and now represented by the summits of the flat and even-topped divides, ridges and hills.

Hills. On the Northern Plain occur numerous hills of accumulation forming the great morainic belts, the result of excessive dumping and heaping up of drift along the margins and between the lobes of the melting ice-sheet. The most impressive examples are found in Steuben, La Grange, Noble and Kosciusko counties, where they attain a height of 200 feet or more, and are as steep and sharp as the materials will lie. Their peculiar forms and tumultuous arrangement give a striking and picturesque character to the landscape.

The Ohio Slope is studded all over with hills of degradation-blocks and fragments of the original plain left by the cutting out of the valleys between them. Some are broad and flat-topped, some narrow, crooked and level-crested, some sharp or rounded, isolated knobs or buttes. These are very conspicuous in the counties of Greene, Daviess, Martin, Crawford, Orange, Washington and Jackson but attain their greatest development in Floyd, Clarke, and Scott where the Silver Hills and Guinea Hills rise to 400 and 500 feet above the valley bottoms. In Brown county the knob topography attains the highest absolute elevation in Weed Patch Hill, and the surrounding region is so rugged as to have gained the title of the "Switzerland of Indiana.” In Benton county, Mounts Nebo and Gilboa are isolated masses of rock projecting above the general level of the plain, and are probably entitled to the name of monadnocks.

Moraines. In addition to the massive and rugged moraine belts already described, there are many morainic ridges of gentle slope and smooth profile, "like dead waves upon the surface of the ocean," conspicuous only upon the map by their influence upon streams. Those which extend along the right banks of the St. Mary's, upper Wabash, Salamonie, Mississinewa, and upper White rivers are typical examples. The southernmost moraine in the state, which enters Vigo, Vermillion and Parke counties from Illinois, is composed largely of a series of broad, low mounds, irregularly disposed upon the plain. In this connection should be mentioned the form of moraine known as boulder belts-long, narrow, curving strips of country thickly covered with large boulders. These occur in the counties of Jasper, Newton, Benton, Warren, Tippecanoe, Boone, Clinton, Hendricks, Johnson, Shelby, Rush, Henry, Randolph, Wayne, Whitley and Huntington.

Kames and Eskers.-These are den and gravel laid down by strong

sheet. Kames are irregular ridges and mounds, having a general direction at right angles to the direction of ice movement, and are found in connection with the massive moraines. Eskers, or "serpent kames," are long, winding ridges of sand and gravel, parallel to the direction of ice movement, and generally extending down a valley of glacial drainage. They mark the course of streams which flowed in sub-glacial tunnels. The valley of Turkey creek, in southwestern Noble county, the Erie-Wabash channel south west from Fort Wayne, and the whole course of the "Collett Glacial Rivet," from Delaware and Madison to Decatur and Bartholomew counties present numerous examples. There are probably many more in the state still unreported.

Closely related to these are sand and gravel streams, plains and overwash aprons, in which the material is spread out over broader areas. Northern Steuben, northwestern Whitley and central Bartholomew counties contain good examples, a few out of a probably large number in the

state.

Dunes and Beach Ridges.-These are hills and ridges of sand or gravel, either blown up by the wind, or built up by the waves along the shores of lakes now withdrawn. The region around the head of Lake Michigan, the Kankakee basin, and the Maumee Lake basin east of Fort Wayne afford fields for more extensive study of these forms.

Valleys.-As before stated, all the valleys of Indiana are the result of stream erosion; most of them by the streams which now occupy them. During the glacial period, however, the streams generally carried much more water than at present.

Gorges, ravines and canyons, are deep, narrow valleys with precipitous walls. They exist in great number and variety throughout the Ohio Slope, occurring along the Whitewater, White and Ohio rivers, and all their tributaries. The eastern tributaries of the Wabash in Fountain and Parke counties flow through very beautiful canyons cut in massive sandstone, often with overhanging walls which, at "The Shades of Death," reach a height of 250 feet.

In valleys of this character rapids and falls are very numerous. They occur upon nearly every stream emptying into the Ohio, and vary in height from a few feet to sixty or eighty. Clifty Falls in Jefferson county and Cataract in Owen county are among the most famous.

All the streams flowing from the glaciated area, have had their valleys flooded with glacial waters, and choked with glacial debris. The effects of this are shown by the extensive terraces of sand and gravel which border their present channels, and mark the beights at which they were once

able to deposit sediment. Between these terraces there are often broad "bottoms" or flood plains which furnish the best corn lands in the world.

Glacial Drainage Channels.-During the melting of the ice-sheet the waters found escape by numerous channels which are not now occupied by any large or continuous stream. A very notable one is the Erie-Wabash channel, which carried the waters of the glacial Maumee lake from Fort Wayne into the Wabash at Huntington. The largest in the state gathered the water from numerous channels in Jay, Grant, Blackford, Randolph, Delaware, Madison and Henry counties into one great stream, which flowed south ward through Hancock, Shelby, Bartholomew, Jennings, Jackson, Scott and Clark to the Ohio at Jeffersonville. In its middle course its valley is forty miles wide and 400 feet deep, narrowing to five miles near its mouth. It has been named the "Collett Glacial River."

Lakes. The surface of the Northern Plain is peppered all over with small lakes which occupy irregular depressions in the surface of the drift, and are especially characteristic of the massive moraines. The whole number cannot be less than 1,000. The largest, Turkey Lake in Kosciusko county, has an area of five and a half square miles.

Marshes and Swamps.-These exceed the lakes in number and extent. The smaller ones are the basins of former lakes which have been filled up with sediment and vegetation. The largest are in the Kankakee basin, and are the remaining vestiges of a glacial lake. Everywhere over the Central Plain the divides are too flat and the slopes too gentle for good drainage, and marshes abound. These, however, have been largely drained by ditches.

Sinkholes and Cares.-Extending from Harrison, Crawford and Clarke counties to Putnam is a belt of limestone which is honey-combed by underground streams producing a great variety of sinkholes, caves and "lost rivers." The sinkholes are basin-like depressions ten to fifty feet deep, and thirty to three hundred feet in diameter, with an opening at the center which leads to some underground passage. In some cases a stream drops into this hole out of sight and emerges again upon the surface many miles away. If the opening has become clogged the basin holds a pool of clear water. Many of the underground passages have been wholly or partially abandoned by the streams which made them, and can be followed great distances. Wyandotte Cave in Crawford county has been explored a distance of twenty-three miles, and rivals in extent and beauty the Mammoth Cave of Kentucky. In Harrison county the rock