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INDIANA UNIVERSITY _ STUDIES

Contributions to Knowledge made by Instruc- tors and Advanced Students of the University

VOLUME VI

Nos. 40-43. January, 1919, to December, 1919

- et ¥ r . 2 > aw e . t . “ oe CAM EF a ~s"\

Lae tiAS >

BLOOMINGTON, INDIANA

Published by the University

The UNIVERSITY STUDIES constitute a series of University pub- lications, in which are published some of the contributions to knowledge made by instructors and advanced students of the

University. At present four numbers are issued a year.

For sale by the University Bookstore, Bloomington, Ind.

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41.

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Table of Contents

VOLUME VI

THE “AMERICAN BOTTOMS” REGION OF EASTERN GREENE CoUNTY, INDIANA—A TYPE UNIT IN SOUTHERN INDIANA PHYSIOGRAPHY. By Clyde A. Malott, Ph.D., Assista:t Professor of Geology, Indiana University.

A StTupy oF HANDICAPPED CHILDREN: BASED ON ONE HUNDRED AND FIFTY CRIPPLED CHILDREN REFERRED TO THE SOCIAL SERVICE DEPARTMENT OF INDIANA UNIVERSITY. By Helen Hare, A.M., Hospital Worker in Robert W. Long Hospital, Indianapolis.

THE SOCIAL ASPECT OF THE CARDIAC CASE: A STUDY BASED UPON ONE HUNDRED FIFTY-FOUR CARDIAC CASES REFERRED TO THE SOCIAL SERVICE DEPARTMENT OF INDIANA UNIVER- sity. By Lela Frances Thompson, A.M.

THE SOCIAL SIGNIFICANCE OF MENTAL DISEASE AND DEFECT: A StTuDY BASED ON THREE HUNDRED FORTY-FIVE MENTAL AND NERVOUS CASES REFERRED TO THE SOCIAL SERVICE DE- PARTMENT OF INDIANA UNIVERSITY. By Helen Hunt An- drews, A.M., Head of the Social Service Department in City Hospital, Louisville, Ky.

Yat Parmer is ee ; Marcu, 1919 pL I i een — : ea :

INDIANA UNIVERSITY STUDIES

MAR 18 1920 |

‘ *», Ya ; E ona: wuss

Study No. 40.

THE “AMERICAN BOTTOMS” REGION OF EASTERN

GREENE COUNTY, INDIANA—A TYPE UNIT IN SOUTHERN INDIANA PHYSIOGRAPHY. By Ctryps A. Matort, Ph.D., Assistant Professor of Geology, Indiana Uni- versity,

% For Sale by the University Bookstore, Bloomington, Ind. Price, 25 cents.

The INDIANA UNIVERSITY STUDIES are intended to furnish a means for publishing some of the contributions to knowledge made by instructors and advanced students of the University. The STUDIES are continuously numbered;- each number is paged inde pendently.

Entered as second-class matter March 27, 1916, at the post-office at Bloomington, Ind., under the act of August 24, 1912. The INDIANA UNIVERSITY STUDIES are published four times a year, March, June, September, and December, by Indiana University, from

- the University Office, Bloomington, Ind. — oe i

INDIANA UNIVERSITY STUDIES Marcu, 1919

VoL. VI

STUDY No. 40

THE “AMERICAN BOTTOMS” REGION OF. EASTERN GREENE COUNTY, INDIANA—A TYPE UNIT IN SOUTHERN INDIANA PHYSIOGRAPHY. By Ctrype A. Matort, Ph.D., Assistant Professor of Geology, Indiana Uni- versity.

oy. 3& fo

QE, eS ~22a] Muse

Submitted in partial fulfilment of the requirements for the degree Doctor of Philosophy at Indiana University.

Contents

PAGE INTRODUCTION, 2: 0) oe. Db be ie ie ee ee eee 3 LocaTION, EXTENT. AND NAME OF THE ‘‘AMERICAN BorroMs’”’.............. 5 DRAINAGE AND TOPOGRAPHY...) 2) 6050 2 ee 6

THE GEOLOGY OF THE ‘‘AMERICAN Bottoms’’ REGION AND THE TOPOGRAPHIC

AND PHYSIOGRAPHIC INFLUENCES OF THE LiTHOLOGIC UNITS............ 7 The Mississippian Strata. 0.3. 2. +0 25 eee 8 The Mitchell Limestone... 5...) eee 8 The Sample Sandstone and Horizon: 2-33... 9 The Beaver Bend Limestone. =). ) The Brandy Run Sandstone Horizon, 3... 10 The Reelsville Limestone <:..+23.4 25... e ee 10 The Elwren Sandstone and Shale..:.-.. 2) dia The Beech Creek Limeston€. — 0.2 2h ee 11 The Cypress Sandstone. 34) 22. $40.2 2 eee 16 The Golconda Limestone and Shale... 2) i eee 18 The Pennsylvanian Strata: 2 00.000 ee ee 19 Ehe Mansfield*Sandstone.-s:. .. 2.4. 20-2 ee ee "i Se eee 19 THE PRE-GLACIAL PHYSIOGRAPHIC HISTORY OF THE REGION................ 21 The Significance of Land Forms... 2.22) =e eee 21 The Kirksville Peneplain...... 0.000 7.2 >. Se eee 22 The Partial Erosion Cycle Succeeding the Kirksville Peneplain..... 23 Eurther Uplift and Stream Trenching. .._...322) ee 26 Valley Filling): . 0.20030. nee A eee 26

Valley Filling Interpreted as a Result of Regional Depression. ... © 27 Valley Filling Interpreted as a Result of the Seaward Extension

of the Master Stream. 62. 0000) 2515.0 29

General View of the Topography and Relief Before the Advent of the Illinois Glacial Lobe... 3... 2.5.30... See 34 Summary of the Pre-Glacial Physiographic Development.......... 35 THE PHysioGRAPHIc [INFLUENCE OF THE ILLINOIS GLAcTAL LoBE............ 36 General Obstruction in Front of the Illinois Glacial Lobe.......... 36 Stream Damming in the ‘‘American Bottoms’’ Region............. 37 Post-GLAcIAL PHYSIOGRAPHIC WORK AND READJUSTMENT...............--- 40 Remowval of the Pleistocene Deposits. ”....._.. 3. eee 40 Development of the Post-Glacial Clifty Creek........>..........3. 43 Development of the “‘American Bottoms”? Dramage.....5= 73... 45 The ‘‘American Bottoms’”’ Basin Specially Preserved... .. ON SY/ SUMMARY co: oP eisde ose s vp ce in Stee a nee Re ae ae Ae 58

3

The ‘‘American Bottoms’’ Region of Eastern Greene County, Indiana—A Type Unit in Southern Indiana Physiography

CLYDE A. MALOoTT, Ph.D., Assistant Prefessor of Geology, Indiana University

INTRODUCTION

THERE are few regions with more diversified physiographic conditions and resulting wealth of topographic detail than southern Indiana. The fairly uniform monoclinal dip of the rock strata to the west-southwest brings to the surface a highly variable succession of strata, each lithologic type having its characteristic topographic forms. Since several erosion cycles have been initiated, only the oldest of which ever neared completion, the physiographic and topographic features have been multiplied and rendered complex. An- other highly important influence has been that of partial glaciation. The Illinois glacial lobes came in from the north on the two sides of the state, reaching as far south as the Ohio River, but coming together or overlapping in the middle of the state only as far south as northern Monroe County, thus leaving a triangular area, with apex to the north, some 5,000 square miles in extent. The effects of the glacial ice over the area covered by it largely determine the topographic features. In the region adjacent to the glacial margin are found some rather peculiar and striking drainage modifica- tions and resulting topographic features. Since the drainage of southern Indiana, especially its middle and western part, is almost exclusively toward the west and south, these drain- age modifications are to be found chiefly on the western side of the unglaciated area.

While there is, therefore, a great variety of topographic forms resulting from the physiographic conditions mentioned above, the complexity is not so extreme as may appear to the

(3)

4 Indiana University Studies

casual observer. The types of rock exposed to the physio- graphic processes give rather distinct regional physiographic strips in succession from east to west. In a region like south- ern Indiana, which has been subjected to minor uplifts from time to time with short periods of stability between, the kind of rock is the controlling conditioning factor. It is easy to see in crossing the urglaciated area of southern Indiana from east to west that both the major and minor features are largely due to the kind orf rock present. It follows, therefore, that any discussion of the physiography must take fully into consideration the areal geology, in so far as the latter is re- lated to the lithologic type. While the type of rock of the various physiographic belts has been a controlling condition, there are also a number of forms, such as high, level-topped dividing ridges, local peneplains, and similarly developed stream trenches, common to all parts of the unglaciated area. With proper care these may be traced thru the various physio- graphic belts, and correlated. Since the major lines of drain- age either rise in the glaciated area to the east, or in the unglaciated area, and pass thru it into the glaciated area to the west or into a stream itself affected by glaciation, there are as a consequence certain other sets of conditions and results tending to give continuity to the physiographic types.

Thus, it will be seen that the physiography of southern Indiana may have had its features determined by any one or any combination of four sets of conditions: first, the type of rock exposed; second, the several uplifts with intervening short periods of stability; third, glaciation on two sides of a triangular unglaciated area; and fourth, the fact that the main elements of the drainage flow toward the west or south from the glaciated region on the east, across the unglaciated area and into the glaciated area to the west, or into a stream that has been affected by glaciation. The physiography of southern Indiana may be expressed in terms of one or more of these four sets of conditioning factors. 3

The locality known as “American Bottoms” in eastern Greene County, Indiana, illustrates all four of the above con- ditioning factors, and may, therefore, be considered as a unit or type of southern Indiana physiography. With these intro- ductory remarks we are now ready to pass to a consideration | of the details of the region in question.

On

Malott: The “American Bottoms” Region

LOCATION, EXTENT, AND NAME OF THE “AMERICAN BOTTOMS”

The area included in the present discussion is represented on two maps, one of which shows the topography and drain- age and the other the geology. The geologic map carries a small insert of Greene County, showing the location of the mapped area within the county. The “American Bottoms” proper are situated in T. 7 N., 3-4 W., and consist of a filled valley about five miles in length and as much as a mile in width. The mapped area includes parts of these townships amma csmall part of IT. 6 N., R. 4-W. The entire mapped area comprises about 40 square miles. It will be scen by reference to the geologic map that most of the area lies within the driftless portion of the state, but that the eastern margin of the Illinois Glacial Lobe affected the western edge. A greater area is mapped than is directly concerned with the phenomena of the “American Bottoms’. Beech Creek valley is In no way connected with the ““American Bottoms’’, but its inclusion on the map gives clearness to the position and succession of the rock formations, and brings out the con- trasted elevations of these two valleys. It will be seen that the presence and position of certain kinds of rock are of the very first importance in preserving the broad, flat surface of the “American Bottoms’, which have resulted from the filling of a pre-glacial valley in front of the Illinois Glacial Lobe.

Just why certain elevated, broad, alluvial terraces adja- cent to streams, or certain broad, filled valleys should so frequently be called ‘“‘American Bottoms” has never been made clear to the writer. The first description and attempted explanation of the “American Bottoms” cf eastern Greene County is by G: H. Ashley in the Twenty-Third Annual Re- port of the Indiana Department of Geology and Natural Resources for 1898, from notes made by C. E. Siebenthal. Ashley does not propose the name “‘American Bottoms” for the broad, flat, filled valley, but says that this name has been given to it. The only other mention of the region in geologic literatures is in Monograph XXXVIII, of the United States Geological Survey, where Leverett, using Siebenthal’s notes, calls attention to the filled valley as having been the site of a glacial lake “now known as the ‘American Bottom’’’. It is not clear whether Siebenthal gave the area the name which it now bears, or whether the name had been previously in use.

6 Indiana University Studies

DRAINAGE AND TOPOGRAPHY

Oniy an outiine of the drainage and topography need be included under this heading, since the topographic map has been prepared expressly to exhibit them. In general, the main streams flow to the west or southwest. Beech Creek flows along the northern edge of the area, and enters Rich- land Creek at the northwest corner. Clifty Creek, heading near the village of Cincinnati, flows west, and after travers- ing a number of remarkable meanders and stretches of sub- terranean drainage, turns southwest into Plummers Creek. The latter, with a course slightly north of west, enters the area toward the southwest, and leaves near the southwestern corner. The headwaters of Ore Creek occupy the middle western edge of the area. Bridge Creek is the principal stream in the “American Bottoms”. This stream is alto- gether peculiar, as it empties abruptly into a cavern in the sandstone bluff on the south side of the valley. Several smaller streams in the western and southwestern portions of the “American Bottoms” are smaller replicas of Bridge Creek. The waters from Bridge Creek and these smaller streams of the ““American Bottoms’, after an underground journey, de- bouch from two or three openings in the sandstone bluff in the northeast quarter of section 34, T. 7 N., R. 4 W., where they form springs in the valley of a stream which flows into Clifty Creek.

The relief of the region varies from 525 feet above sea level in the broad valley of Plummers Creek to over 800 feet above sea level on the crests of a number of gentle promi- nences along the ridges between the main drainage lires. In the region of Cincinnati, where the main streams of the region head, an elevation of 900 feet is reached. Thus, the maximum relief of the area is about 375 feet. A representa- tive difference in elevation between the ridge and valley may be seen in the vicinity of Ridgeport, where the crest of the ridge is approximately 800 feet, and the valley of Beech Creek is about 550 feet above sea level. This gives an im- mediate relief of approximately 250 feet. The ridge between Bridge and Clifty creeks is also approximately 800 feet in elevation, and Clifty Creek valley is 575 feet above sea level, giving a relief difference of about 225 feet. Bridge Creek valley, or the “American Bottoms”, lies approximately 650

Malott: The “American Bottoms” Region i

feet above sea level; so that its elevation is about 100 feet greater than the adjacent valleys. A brief inspection of the topographic map reveals at once the presence of two west- wardly extending, gently undulating ridges, formed by the bifurcation of a single broad ridge near Cincinnati. From these two ridges numerous spurs extend out to the north and south. The deep valleys of Beech and Clifty creeks he on the north and south respectively, while the broad elevated valley of the ‘‘American Bottoms”, with its peculiar drain- age, lies between the two ridges. To the southwest, north of Koleen, is a broad ridge between Plummers and Clifty creeks. This ridge is terminated rather abruptly by the narrow valley of Clifty Creek, which cuts it in two, leaving a subdued rem- nant on the west side. It is in this region that the most prominent cliffs appear. Sheer descents of 50 to 75 feet are found, and these are responsible for the name Clifty Creek. Further discussion of the drainage and topography will be given in the section on the detailed description and inter- pretation of the physiographic features of the region.

THE GEOLOGY OF THE “AMERICAN BOTTOMS” REGION AND THE TOPOGRAPHIC AND PHYSIOGRAPHIC INFLUENCES OF THE LITHOLOGIC UNITS

Under this head it is the intention to emphasize the stratig- raphy of the region with special reference to the lithologic succession. Formation names will be used mainly for the identification of the horizons under discussion, and for the purpose of calling attention to such strata as are clearly re- sponsible for topographic and physiographic forms. Since the position of certain strata at critical levels is important, the general structural conditions are also discussed. In this respect it may be said that the general dip to the west- southwest at the rate of approximately 30 feet per mile car- ries the higher strata of the eastern part of the area to lower and lower positions to the west and south. As in the dis- cussion of drainage and topography, attention was directed to the topographic map, so here attention is called to the geologic map, and especially to the areal distribution of the strata and to the stratigraphic column at the right of the geologic map. This column shows by the usual conventional

8 Indiana University Studies

signs the lithologic succession of the solidified strata, as well as the corresponding symbols used to indicate the areal dis- tribution of formations on the map. It was not found con- venient or practical, especially in the case of the thinner members, to show each lithologic unit on the map. It is seen that the bedrock strata which occur in the region are of upper Mississippian and lower Pennsylvanian age, ard that these two periods are separated by a disconformity.

The Mississippian Strata. The Mississippian strata found in the region are confined entirely to the Chester Series, and consist of limestones, shales, and sandstones. Recent work, yet unpublished, on the Chester Series of Indiana has led to a definite naming of the series of formations. This work was done by the writer and J. D. Thompson, of the Empire Gas and Fuel Company, during the summer of 1918. The various formations as they occur in the region here under discussion will be given the names as determined by this latest work on the Chester of Indiana. This work consists mainly in the correlation of the formations with those of Kentucky, following the nomenclature of Butts, of the United States Geological Survey, whose work was published by the Kentucky Survey in 1917. Several new formational names are introduced for the Indiana region, some of which have no representatives in Kentucky. No change has been made in the divisions and nomenclature below the top of that great thickness of limestone known in Indiana as the Mitchell lime- stone, the upper part of which belongs to the Chester and one lower part to the St. Louis.

The Mitchell Limestone. The Mitchell limestone is really a group of formations, but makes one great lithologic unit very difficult to divide in a mapable way. The upper part in Indiana is equivalent to the Gasper Odlite and the Fredonia Odlite of Kentucky and is Chester in age, while the thicker lower part is the St. Louis limestone. Only the uppermost part outcrops in the “American Bottoms” region.

The upper part of the Mitchell limestone is found near the head of Beech Creek valley. It consists of thin layers of compact sub-odlitic limestone, and rises approximately 25 feet above the floor of Beech Creek valley, in section 9. To the west the dip carries it beneath the alluvium of the stream. To the east along Beech Creek, in section 10, the Mitchell

Maiott: The “American Bottoms’ Region 9

limestone does not appear above the valley alluvium, on ac- count of the presence of a disconformity and the consequent deposition of the succeeding sandstone in its place.

The Mitchell limestone to the east of the region under discussion forms a surface rock of high importance from a physiographic standpoint, being responsible for a structural peneplain characterized by magnificent subterranean drain- age systems and an attendant highly developed karst topog- raphy. Since its outcrop is limited to a very small part of the area under discussion, and its position is for the most part at or below drainage level, it is of little physiographic influence here.

The Sample Sandstone and its Horizon. Overlying the Mitchell limestone are gray and blue shales containing lenses of sandstone, sometimes quite massive and attaining a thick- ness of from 10 to 30 feet. This shale and sandstone horizon fills the interval between the Mitchell and another limestone from 5 to 20 feet thick, and occupies the position of the Sample sandstone. The Sample sandstone receive its name from its excellent exposures near Sample, Breckin- ridge County, Ky., where it occurs as a division in the Gasper Oohte.' The limited thickness of 20 feet, and the small areal outcrop of the shales and the associated lenses of sandstone render it of little importance physiographically in the region under discussion.

The Beaver Bend Limestone. The limestones mentioned in the preceding paragraph as succeeding the Sample sand- stone horizon is a bedded limestone, often having massive beds, and is highly odlitic. It is conspicuously jointed, and, on this account, gathers waters into concentrated streams from the porous sandstone usually found above it. These waters come out as springs at the base of the limestone on the underlying impervious shale. Field work has demon- strated that this limestone is found consistently practically from the Ohio River northward as far as the Chester Series extend, into Putnam County. Locally, however, it appears to be separated by only a shght interval from the top of the Mitchell limestone; and in a number of places it has been removed by the erosion which in certain places extended down

1 Charles Butts, Mississippi Series in Western Kentucky. Kentucly Geological Survey. Wale,

2—16903

10 Indiana University Studies

into the Mitchell limestone. The name proposed for this lithologic unit is the Beaver Bend limestone from a con- spicuous bend in Beaver Creek just east of Huron, Lawrence County, Ind., where the Baltimore and Ohio Railroad cuts thru a spur on the inside of the bend. Its entire thickness of 14 feet may be seen there near the bottom of the cut. It is the Upper Gasper of Kentucky, as seen in the region of Sample, where the Sample sandstone divides the Upper Oolite into an upper and lower member. The Beaver Bend lme- stone appears locally thruout the length of Beech Creek, ex- cept to the east, where the Elwren sandstone in an unusually thick mass comes down and occupies the position of the eroded portions of several members, including the upper part of the Mitchell limestone, as mentioned above.

The Brandy Run Sandstone Horizon. Above the Beaver Bend limestone occur some 10 to 20 feet of gray-blue shales and sandy shales, overlaid in turn by another thin limestonc. This interval represents the stratigraphic position of a sand- stone which farther south in Indiana becomes quite promi- nent, and reaches a thickness of 30 to 50 feet. The latter is excellently developed in the region of Marengo, on Brandy Run Creek, and the name Brandy Run sandstone is proposed for the formation. It thins out south of the Ohio River, and is absent beyond Breckinridge and Meade counties, Ky. The horizon has little physiographic interest in the region under discussion.

The Reelsville Limestone. The thin limestone mentioned above, ‘which overlies the horizon of the Brandy Run sand- stone, is typically only 2 feet thick. It is a compact to semi- crystalline limestone, frequently quite odlitic in texture, and almost always sub-odlitic. It contains considerable pyrite which causes it to weather to a-characteristic red color. The remarkable feature of this limestone is its persistence over a wide area. It is found at Reelsville, Putnam County, Ind., from which locality it is proposed that it be named. From there southward it forms a single consistent ledge, until middle Crawtord County is reached, where several other thin ledges come in on top of the main one. It can be traced over a wide area in Meade and Breckenridge counties, Ky., and is there rarely over 10 feet in thickness. Its fauna is closely allied to that of the Gasper Odlite. - It is of little or no im-

Malott: The “American Bottoms” Region i

portance physiographically in Indiana. Its outcrop is con- fined to Beech Creek valley in the region here considered, and it is only infrequently seen in position.

The Elwren Sandstone and Shale. The lthologic unit succeeding the Reelsville limestone consists of one or more members of sandstone and frequently considerable thicknesses of shale, the whole having a total thickness of 40 to 50 feet. The name proposed for this formation is the Elwren sand- stone, from the vicinity of Elwren in western Monroe County, Ind., where excellent exposures are to be seen in the cuts of the Illinois Central Railway. It fills the interval between the thin Reelsville limestone and the next limestone above. The Elwren sandstone and shale unit is represented on the geologic map by a single convention. In the region of the “American Bottoms” it consists of a sandstone from a few feet up to 30 feet in thickness, and a gray-blue shale, with a maroon streak extending up to the overlying Beech Creek limestone, or to another sandstone member near the top. The latter in places attains a thickness as great as the lower sandstone member. The upper sandstone is thick where the lower sandstone is thin. This latter condition is shown in the typical stratigraphic column taken from Ray’s Cave sec- tion along Beech Creek near Ridgeport. The sandstone is usually bedded, but is occasionally massive. The Elwren sandstone and shale unit outcrops on both sides of Beech Creek valley thruout its course, and along the upper part of Clifty Creek valley. North and east of the extreme north- east corner of the mapped area the Elwren sandstone has unusual thickness, occupying the position of several of the lower units which had been eroded away previous to the deposition of the Elwren sandstone. Topographically the Elwren sandstone gives rise to local benches where it takes on the massive phase, as may be seen in the northwest quar- ter of section 7, on the north side of Beech Creek. Since the sandstones are medium to fine grained and usually con- tain considerable clay, they form slopes rather than bluffs and cliffs.

The Beech Creek Limestone. The next stratigraphic unit in the Chester Series is the Beech Creek limestone. This name is proposed for the limestone unit which has heretofore been called the “Middle” or “Second” limestone of the Ches-

WZ, Indiana University Studies

ter Series of Indiana, according to Kindle, Hopkins, Ashley, and others. It receives its name from its excellent exposures along Beech Creek in the region under consideration. This

Vic. 1. Mouth of Rayv’s Cave, near Ridgeport. Shows entire thickness of Beech Creek limestone (below) and Cypress sandstone (above). Photo- graph by P. B. Stockdale.

limestone has a narrow areal outcrop, but it is given on the geological map a separate convention. It consists of two or more massive to thin bedded ledges with a total thickness of

Malott: The “American Bottoms’ Region 13

8 to 24 feet, and a typical thickness of 12 feet. In the region considered in this discussion it attains its maximum thick- ness of 24 feet, as seen in the Ray’s Cave section (Fig. 1). Thruout the region of the “American Bottoms” it must have a thickness of 20 feet or more, and in places may possibly exceed its thickness in the Ray’s Cave section. Everywhere thruout the state from Owen County south to the Ohio River, where the Beech Creek limestone is exposed in weathered outcrops, it presents a ragged face made up of cubical chunks of limestone. It is a gray, compact to sub-oolitic, and often semi-crystalline limestone, frequently locally quite completely odlitic, and contains large numbers of brachiopods, especially of the genus Productus. Of the succession of Chester lime- stones, none contains such a number of large, well-preserved crinoid stems standing out prominently on the weathered faces as the Beech Creek. This feature along with the hackly, cubical weathering gives it such distinguishing characteristics that it can be easily told from any of the other Chester lhme- stones in the state. In the “American Bottoms” region, there is an added thickness at the top. This added thickness con- sists of coarse, crinoidal ledges with a considerable admixture of sand and clay. These upper ledges weather a distinct yellow. It would appear that the area may have been a local basin, or have led into one of considerable dimensions to the west. These upper yellow ledges contain a number of species of Archimedes.

The Beech Creek limestone is quite persistent thruout the outcrop of the Chester in Indiana. Only locally is it absent where the strata are sufficiently high for its occurrence. Across the Ohio River it thins out and farther south is absent. At Sample, Ky., in the shale some ten feet above the Reels- ville limestone is a thin ledge of limestone about 4 inches thick that probably represents the Beech Creek. Likewise, in a railroad cut some two miles east of Garfield in Breckin- ‘ridge County there is a ledge 6 inches thick which is its probable representative. A short distance away from this latter place the overlying massive Cypress sandstone comes down considerably below the horizon of the Beech Creek. It may be added that toward the eastern outcrop of the Chester in southern Indiana there is conclusive evidence that the upper Chester formations overlap the lower ones, and this

14 Indiana University Studies

overlap is quite notable in the Cypress sandstone, so that this latter formation may be expected to lie on lower and lower strata to the east.

The Beech Creek limestone outcrops along Beech Creek and its tributaries high above the valley floor, and along Clifty Creek to its junction with Plummers Creek valley. In the latter case it comes down to the valley level, and in places is hidden by the valley alluvium. It outcrops only in the easternmost ravines of Bridge Creek, and is below the level of the flat “American Bottoms” valley. In the northeast corner of the area it does not seem to have been deposited at all. It is a rather curious fact that the area where the Beech Creek limestone has not been deposited should be coterminous with the area characterized by the development of the massive phases of the Elwren sandstone and the notable disconformity at its base. This raises a question the discussion of which cannot be undertaken in the present paper.

The Beech Creek limestone is of great importance from both the topographic and physiographic standpoints. Along its outcrop it frequently stands out as a wall-like bench, partly on account of the shale which characteristically underlies it, and partly because of its recession en masse on weathering. Its highly jointed condition allows it to collect waters from the overlying sandstone into concentrated streams, the out- flow of which in steep-headed ravines and gorges makes it perhaps the most extensive and persistent spring-bearing horizon in the Mississippi valley. It possesses this character because of its relation to the massive overlying sandstone which has a high porosity. These springs often yield a con- siderable volume of water, and the characteristic steep-headed gorges with their high walls of solid rock are common thruout the region of the outcrop of this formation, especially where the limestone is rather. high above the drainage level. The Ray’s Cave gorge is typical (Fig. 1). Another example, weil outside the region in question, is “The Gorge’ southeast of French Lick, whose scenic beauty has been commercialized, so that any visitor who cares for an out-of-town dinner may partake of one of the excellent chicken dinners for which the place is noted. As may be inferred from the presence of these gorges with such large volumes of water coming from their steep-walled heads, the solution of the limestone along

Malott: The “American Bottoms” Region 1S)

the joints has frequently enlarged them to caves of consider- able size and length, considering the limited thickness of the formation. Ray’s Cave, near Ridgeport, is a cave of very uniform width and height, following the joints strictly, and turning frequently at sharp angles. This cave may be easily followed for a distance of about 1,000 feet, to a point where further progress is arrested by a mass of great sandstone blocks fallen from above. This distance, however, must rep- resent only a small part of the total length of the cave, since a large volume of water comes from under the fallen debris.

Just how important this limestone is physiographically will be clear when it is realized that the peculiar drainage conditions in the “American Bottoms” are due to its presence at critical levels. Bridge Creek and its smaller associates do not empty their waters into the sandstone bluff for any other reason than that the Beech Creek limestone is immediately below it. This limestone is, in fact, only 10 feet below the point where the waters of Bridge Creek enter the sandstone, tho the limestone itself is nowhere visible about the margin of the “American Bottoms” flat. Had it not been for the presence of this 20 odd feet of limestone at this particular level, there could have been no subterranean drainage, such as occurs, nor could there have been preserved the unusually broad, filled valley, which, for the most part, is wholly intact. The physiographic effect of this limestone at a critical level is seen again in the southwest quarter of section 35, along Clifty Creek, where the limestone has been carried by the dip to slightly below the level of the stream, permitting the local development of subterranean drainage by the waters of Chlifty Creek. Only the flood waters pass around the great double meander at this point. The water passing thru this subterranean passage, or rather passages, along the enlarged joints in the limestone is lost to view for a distance of about one-fourth of a mile, and nearly 150 feet beneath the crest of the ridge above. This underground passage-way of Clifty Creek is in its initial stage, but we can see that it must finally cause the complete abandonment of the surface chan- nel, leaving the great double meander of a dry valley sunk deeply into the strata, the product of a stream which has entrenched itself since the invasion of the Illinois Glacial Lobe into the region (see Fig. 2).

16 Indiana University Studies

The Cypress Sandstone. Cypress sandstone is the name applied to the massive, usually non-bedded, sandstone, over- lying the Beech Creek limestone. This sandstone is the most

1 | Je LOCATION

4 OF PICTURE "| ONLY THE FLOOD WATERS

| PASS OVER THE BED OF >= CLIFTY CREEK AT THIS PLACE. THE BEECH CREEK LIMESTONE ALLOWSTHE PASSAGE OF THE NORMAL WATERS BY A SUBTERRAN- EAN CUT-OFF ONE- FOURTH MILE SOUTH.

Fic. 2. Bluff on Clifty Creek, showing contact of the Beech Creek limestone and the Cypress sandstone. This part of the post-glacial stream is now being abandoned in favor of subterranean drainage. Photograph by P. B. Stockdale.

persistent sandstone of the Chester Series, and is only locally absent, shale being sometimes substituted for it where its

Malott: The “American Bottoms’ Region Le

horizon appears. It is normally 30 feet thick along its whole outcrop in Indiana, but is occasionally thinner or thicker. The Cypress sandstone receives its name from its excellent exposures along Cypress Creek, southwestern Johnson and Union counties, Ill., where it attains a somewhat greater thickness than in Indiana.’ It has been traced by Butts around the crescentric outcrop of the Chester Series thru Kentucky to the Ohio River.’ Field work in 1918 by J. D. Thompson and the writer has proved its wide extension in Indiana. It appears everywhere its horizon is due. Evidence is at hand to show that it is an overlapping formation, and that it is perhaps the most continuous and widespread of all the formations in the Chester Series within the limits of its horizon.

The Cypress sandstone is usually a medium-grained sand- stone, tho often quite coarse; it is yellowish to whitish in color, except along its well-developed joints, where it assumes a reddish brown color due to the concentration of iron oxide. It is usually massive and non-bedded, but laminated, and except along the joint planes and exposed surfaces, quite friable. Since the rock is so well cemented along the joint planes, its outcrop often exhibits great broad faces and rec- tangular blocks along the wall-like outcrop (Fig. 2). In the “American Bottoms” region it is from 30 to 40 feet thick, and rests everywhere directly upon the Beech Creek limestone. It is usually cross-bedded near the contact (Figs. 1 and 2). Toward the top it frequently becomes thin bedded, and rapidly grades into the blue-gray to olive shale that underlies the Golconda limestone.

The Cypress sandstone is well developed high above Beech Creek valley along its middle and lower course. It is found everywhere along Clifty Creek, reaching the valley level along the lower course of the creek, and in conjunction with the Beech Creek limestone causing characteristic bluffs and cliffs (Figs. 2 and 3). It everywhere marks the rim of the “American Bottoms’, usually causing an abrupt rise from the monotonous valley flat.

The Cypress sandstone, as indicated above, is everywhere an important topographic and physiographic factor, ranking

-H. Englemann, Geological Survey of Illinois. Vol. I, 1866. 3 Charles Butts, Mississippian Series in Western Kentucky. Kentucky Geological Survey. 1917.

3—16908

18 Indiana University Studies

next to the Beech Creek limestone in this respect in the “American Bottoms” region. It has a wall-like appearance along the streams, whether it be next to the valleys or high up the valley slopes. Since it is overlaid by shale it gives rise to rather sharp local benches, often of considerable breadth where erosion has removed the overlying material down to its resistant top. These benches have been mistakenly interpreted as local peneplains developed in the region where the sandstone is to be found. They are seen prominently above the abrupt slope produced by the sandstone where it rises above the “American Bottoms’. To the west the benches become considerably lower on account of the dip of the strata. Such benches are conspicuously developed on the north side of the “American Bottoms” in section 23. The streams of the ‘“‘American Bottoms’? pass into cavern-like openings de- veloped in this sandstone, owing to the undermining of the sandstone by the weathering and solution of the underlying limestone, and the corrasion by the inflowing waters. The cave-like openings of these stream inlets are among the most striking phenomena of the entire region (Figs. 5, 6, and 7). On the ridges in the eastern part of the area, a number of broad, fairly extensive sags are developed on the Cypress