Report of the Naturalist of the Wabash Academy of Sciences.
(Proceedings of the 1855 Wabash Academy of Sciences, p.11-18)

Since our last meeting, I have corresponded with many of the reputed men of science of this and other western States, soliciting contributions from their pens, and inviting them to cheer us with their presence today. But few have replied to our invitations, and those but to inform us of the reasons that induced them to forego the pleasure of meeting the Academy.
As a matter of scientific interest, and as a field mainly unexplored, I propose to devote the present report to some

OBSERVATIONS ON THE TOPOGRAPHY OF INDIANA.

The Topography of a country is intimately connected with, if not indeed, dependent on, its geological character altogether. And on the two combined -- that is, on the interior structure and superficial configuration of a country depends to a great extent, the character of that country, and the place its inhabitants will occupy among the peoples of the earth.
After the invention of the steam engine, the great coal fields of England have made it the manufacturing metropolis of Europe, if not of the world. So the lines of Trapean upheaval that bisect her numerous water courses, creating rapids and fall of water, have made New England what she is in the scale of manufacturing importance. In Indiana, there is no eruption of trap, or other exposure of primitive rock, hence our comparative uniformity of surface and tameness of scenery.
The strata of Indiana has a general dip to the westward, amounting to a mean of about 40 feet to the mile. South of the meridian of Bloomington the dip gradually inclines to

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the north of west, until on reaching Evansville, we have the line of greatest inclination bearing west 20 degrees north; while on the north of that meridian, the line of dip inclines to the south of west in about the same proportions, so that the outcrop of the several formations in this State, are not lines, but segments of a great circle concentric to each other. This is true of all the lines of outcrop westward of the junction of the cliff rock with the lower Silurian. This line, resting on the Ohio river near Madison, passes north, trending gradually to the east until it passes into Ohio near Union. The Silurian formation lying eastward of this line, gives to the country a topography marked by long, gentle slopes, and although the hills are numerous, and often attain an elevation of between 400 and 500 feet above the level of the Ohio River, yet they are seldom very steep, and never precipitous. The loose, shelly character of most of the rocks of this formation, afford poor reservoirs for retaining water, and consequently, durable springs are scarce in this region, and the smaller streams are merely dry beds most of the summer months. This is true, however, of only the southern portion of this section. As we advance northwardly, the summits of the hills and the table lands become covered with heavy drift deposits, whose lower member of dark marlite, or boulder clay, affords impervious material for great reservoirs of water, filling the interstices of the incumbent gravel. -- Hence the northern portion of the Silurian section of Indiana is well supplied with spring and well water, generally free from foreign substances, except carbonate of lime.
Extending westwardly from the line of the Silurian, to a line drawn from the Falls of the Ohio by Columbus, Indianapolis, Delphi, and Monticello, we have a section of country built upon the cliff rock of the Ohio geologists -- the Niagara limestone of Hall, and probably the equivalent of the upper Silurian of the English writers.
The distinctive feature of the topography of this section is its bold precipitous bluffs and deep narrow ravines which form the channels of all the streams. Broad, level plateaus and perpendicular or overhanging cliffs take the places of

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the gently sloping hills of the Silurian. North of Columbus, however, the great depth of drift has concealed the rock, except where the Wabash River, and its larger tributaries have cut their channels through it, and exposed the underlieing limestone. We have as yet no means of ascertaining the depth of this formation through much of the central and northern portion of the State. An artesian boring in the vicinity of Indianapolis, sunk through the drift, is a desideratum of considerable scientific importance.
An argillaceous sandstone overlies the cliff rocks, and outcrops to the westward of it. It is of this material that the Knobs of Floyd and Washington Counties are formed; and the almost mountainous elevations of the eastern part of Lawrence, the most of Brown, and a part of Morgan Counties consist of this stone. It gives a bold, mountain-like topography to the section of country underlayed by it, and where sufficient level surface occurs to form reservoirs of proper size, the country abounds in springs of very pure water.
Interposed between this formation and the member below it is a deposit of black aluminous slate from fifty to a hundred feet in thickness. To the existence of this slate, and to the very fragile character of the overlieing sandstone, I attribute that rather remarkable topographical phenomenon, the Silvercreek valley in Floyd and Clark counties. This valley extends from the foot of the Falls of the Ohio, in a direction nearly north, a distance of more than 20 miles; bounded on the west by a bold escarpment of abrupt hills, attaining a mean elevation of between 500 and 600 feet above the valley. From the base of this range of knobs, the valley gradually rises toward the east, with about the ascent which the dip of the underlieing limestone would give it. This topography indicates that this valley is the result of denudation. Originally, the slate cropped out near the summit of the highland in Clark County, some 15 miles east of the Knobs, and the sandstone lieing upon it filled the valley to the level of the two margins, east and west. But the rapid currents of the drift period cut away the fragile slate, and thus undermining the sandstone, bore it away in com-

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minuted fragments, till the present bold escarpment presented an effectual barrier to farther encroachments in that direction.
The characteristic feature of the mountain, or carboniferous limestone formation which succeeds this sandstone, is the frequent occurrence of what are denominated "sink holes" by the people of this region. They are inverted cones or funnel shaped cavities, sometimes irregular in their outlines, but most generally approaching to a circular form. At the bottom of the concavity there is always an opening communicating with subterranean passages, by which the surface water in time of heavy rains, is conducted downward to fill the great reservoirs that supply the large springs peculiar to this formation. The principle on which these excavations are made is a very simple one. At first, a mere fissure exists in the stone beneath, through which the rain water from the surface, fully saturated with carbonic acid finds its way downward. But water charged with free carbonic acid is a rapid solvent of limestone. By this process the exposed surfaces of the fissure are rapidly carried away by the currents of descending surface water, thus continually widening the passage, until the incumbent earth begins to fall into it, which in turn is borne away by the increased volume of water from the funnel shaped depression on the surface thus produced, until the face of the country becomes dotted over with these "sink holes," and subterranean caverns abound. It is in this formation, and induced by this process no doubt, that the great Mammoth Cave of Kentucky is formed. Numerous caves are found in the Counties of Crawford, Harrison, and Orange in this State. Many of these remain but partially explored, but enough is known of some of them, to justify the assertion, that in them, the great Kentucy cavern will at some day not very distant, find a formidable rival.
A few weeks ago, we had the pleasure of spending a day in Wyandotte Cave, a few miles distant from the town of Leavenworth, on the Ohio river. A minute description of it, for want of room, cannot be embodied in this report. -- Suffice it to say that the extreme distance attained, from the most southwardly to the most northwardly point, is about 7

[Incorrect spelling of "Kentucky" is actual text.]

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miles. The passage, in general, is wide and lofty. A few points, however, have to be passed by creeping. We observed several magnificent chambers, whose ample proportions and lofty domes decorated with the most fanciful fretwork of stalactites, sometimes beautifully variegated, but commonly of the purest white, were indeed sublimely beautiful.
A lizzard about three inches long, and without eyes, was the only living animal we found in it. It was inhabiting a niche in the rock, about two miles from the entrance. How it came there, and on what it subsisted, were questions we were permitted to depart without solving. The temperature of the air in the cave was 53° Far., which we suppose to be uniform.
The carboniferous formation which embraces the south- western portion of the state, is less mountainous that coal districts usually are. Indeed, the great Illinois coal field, as it has been called, is comparatively a level plain, and much of it, contrary to the usual rule, is covered with a soil of great fertility. Both these peculiarities are to be attributed to the influences of the drift period. The fragile sandstone and shales of the coal measures were easily cut down and borne away by the mighty currents of that last of physical revolutions that have passed over the globe. This agency seems to have operated with more force in the northern section of the coal field. Consequently, as we pass toward the Ohio River, the drift deposit thins out -- the hills become more lofty -- show fewer marks of denudation, and the soil being formed from the decomposition of the underlieing sandstone and shale, is much less productive than that farther north, where it is formed from the debris of primitive rocks -- our promiscuous northern drift.
There is a portion of this State, bordering on Lake Michigan, which cannot be referred to either of the classes in the foregoing topographical arrangement. This, as I intimated in my last report, furnishes strong presumptive evidence of having been reclaimed from the Lake at a period not very remote -- at least, not anterior to the drift epoch. Further examination exposes a remarkable fact in relation to this

[Incorrect spelling of "lizard" is actual text.]

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section. The line of the New Albany R. R. after leaving the lake, passes through a belt of lake shore sand, crossing one or two strips of prairie marsh, till at the distance of 5 miles from the shore, it ascends a strong grade and enters a heavy forest, differing alike from the pine growth of the lake margin, and the oak openings further south. At 7 miles distance, the level of the Calumie is 100 feet above the lake. Here the drift formation appears, consisting as usual, of clay, gravel, boulders, &c. With the same formation, the surface continues to rise for the distance of 4 miles beyond the Calumie, where it attains an elevation of 235 feet above the lake level. From this point to the Kankakee, there is a descent of 156 feet, making the surface of that stream 79 feet above Lake Michigan. The boulders continue to appear occasionally along the road to Hog Creek, 10 miles south of the summit, where they disappear at about the same elevation at which they were first observed. From thence the lake shore sand is found wherever the heavy, peaty soil of the prairie has not concealed it, till we arrive at a point 45 miles south of the lake, when the boulder drift appears suddenly at an elevation of about 25 feet above the Kankakee, or 104 above the lake.
For these facts I am indebted to the politeness of Chas. S. Woodard, Civil Engineer on the N. A. & S. R. R.
These data afford the conclusion that Lake Michigan, at a period not very remote in the past, stood at a level between 90 and 100 feet above its present surface. But the Kankakee and Desplaine, whose confluence forms the Illinois river, lie at a level of less than 80 feet above the lake; hence this great inland sea must at that time have stood from 15 to 20 feet deep at the rapids of the Kankakee, and at Joliet. A large island divided the outlet of the lake into two channels -- a northern channel following the course of the Desplaine, and a southern one along the depression of the Kankakee. -- This island stretched from N. E. to S. W. Its length I have not yet ascertained; its breadth on the Railroad line is about 15 miles, and its greatest elevation above the ancient shore 140 feet. That this state of things once existed -- that Lake Michigan once discharged its waters through the Illinois and

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Mississippi into the Gulf of Mexico is a conclusion resting on the same kind of evidence that sustains every conclusion in geology. The geologist, reading the stony records of the profound past, finds the fossil remains of things that were, but are not, yet, on this evidence, he hesitates not to affirm that big uncouth Saurians fished around the bays and estuaries of unknown seas and continents -- that the huge bat- like pterydactyle once flitted through the evening air, more than realizing the horrors of the winged dragons of the middle ages. Now in this deposit of lake sand, we have as truly a FOSSIL LAKE, as the bones of the Mastodon is a fossil animal, and it is just as logical to infer the existence of the original in the one case, as in the other. Corroborating this conclusion, we have the evidence everywhere along the Illinois river, that once a much larger volume of water was discharged through its channel than now passes. But this conclusion pre-supposes that the whole chain of northern lakes were elevated proportionally above their present level, or that the straits of Mackinaw were originally closed. I think the latter the more rational conclusion. The formation at Mackinaw, according for Foster, is the lower Silurian, corresponding with the Trenton and Hudson river groups of Hall, and the Cincinnati blue limestone of Locke.
Now a narrow isthmus of this rock, washed on one side by the waters of Huron, and exposed on the other to the waves of Michigan, beating against it an elevation of near 100 feet above the water on the opposite side, it would require but a very slight convulsion to break down so frail a barrier, and thus sink Michigan and Huron to a common level, and expose its southern bed as dry land, thus cutting off its tribute of waters from the Mexican Gulf, and swelling the flood of the St. Lawrence.
The relative date of this great change we ascertain on the principle of superposition. The sand formation overlies and rests upon the drift beneath, which is frequently reached in that region in digging wells. This justifies the conclusion that the sand was deposited since the drift epoch, which was, as is universally admitted, the last of the series of great phy-

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sical revolutions to which this globe has been sujected. Consequently, we must regard the draining off of Lake Michigan as a local phenomenon occurring since the diluvial period. The direction of the St. Joseph of the Maumee indicates another very important change that has occurred in the topography of northern Indiana. A glance at the course of that steam in relation to the Upper Wabash and valley of Little River, will at once suggest the probability that it was originally the main source of the Wabash.
The general direction of the St. Josephs of the Maumee, is from the north-east toward the south-west. The St. Mary's coming from the south, when it reached the vicinity of Fort Wayne, so nearly approaches what was originally the Wabash, or at least its northern branch, that high floods, or other natural agencies broke down the narrow strait between them, and the bed of the St. Marys being a few feet the lowest, the St. Josephs forsook its channel for that of the Maumee.
A dam of only about 12 feet in height now throws the waters of the St. Josephs through its original channel, the valley of Little river, down which descends the Wabash and Erie Canal. This change has occurred even more recently than that in relation to Lake Michigan. In the days of Father HENNEPIN and the early French voyagers, the birch canoe of the red man navigated the Little river valley from the Lake to the Wabash, at the time of Spring freshets, and at all other times when the streams were swollen.

R. T. BROWN, Nat.

Incorrect spelling of "subjected" is actual text;
variations of Joseph(s) and Mary(')s is actual text.)

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Geology Library, Indiana University Bloomington