The most widespread mineral -resource in this area is the limestone for building purposes. From Chapter III it is seen that beds of limestone form a part of every formation which outcrops in the area. Any of these which are thick enough may be used in walls, but most of the formations contain so many thin beds, or so much shale, or both, that the handling of such material would render quarrying unprofitable.
Quarries in the Fairview Formation - Practically all the quarrying on a commercial scale is done in the Fairview, and most of it in its upper portion, the Fairmount member. In the upper fifty feet of this formation there is more limestone than shale, perhaps twice as much, while below that in the Mount Hope member the proportions are almost reversed. Throughout both members of the Fairview formation, a fair proportion of the limestone layers have a thickness of more than four inches, some being as much as seven inches thick, and an occasional one nine or even ten inches. In locating a quarry it is desirable to find as many thick beds as possible within a narrow vertical range so that the handling of discarded material will be as small as possible. Hence most of the quarries near Cincinnati, and the principal ones at Hamilton, are well up on the hillside in the Fairmount member. Just south of Coke Otto considerable quarrying has been done in the lower or Mount Hope member at the foot of the west bluff. The amount of discarded material here is so great as to make quarrying unprofitable except for local work.
Character of the Stone.-The limestone of this locality has the advantage of occurring in beds whose thicknesses continue fairly uniform for such short distances as the length of a quarry, though this is not true for long distances. The upper and lower faces of the blocks are therefore parallel and need no trimming. The other four faces must be trimmed, because the joints which divide the bed into natural blocks run very irregularly.
The color of the fresh limestone is a decided blue but adjacent to the joints the surface of the block is in many cases colored brown or yellow by oxidation. Generally this discoloration is superficial, and, therefore, does not show on the trimmed edge of the block. Where it is deep the block is not used in good walls.
Uses.-This stone is universally used for foundations in this community, except in some cases where ornamentation or variety is the chief consideration. It has also been used for a number of churches and other monumental buildings, such as the Art Institute in Cincinnati. (Pl. VII-B). With a little care in assorting blocks of different thickness, the blocks may be arranged in the wall in a pleasing pattern. The stone neither stains nor fades.
These advantages are sufficient to bring the stone into general use locally, but not to make of it an article of commerce outside the localities where it is quarried. For ornamental purposes and variety, a considerable amount of stone is imported, especially of the Dayton limestone and the Bedford limestone of Indiana.
Of the material discarded in quarrying, the share has no value except for filling. The limestone is almost universally used in road making. The supply of such road material from the culls of quarries and from the grading of streets, etc., is very large, but in addition. to this, some limestone is quarried for this express purpose. As a foundation for roads and streets it is highly satisfactory. It is also satisfactory as a surface material for macadam roads not subject to severe wear, but under heavy wear it rapidly passes into a fine dust which burdens the air and is harmful to man and beast as well as to vegetation. In cities it is intolerable except when oiled. On the other hand, when treated with a suitable grade of oil it makes a smooth, elastic, and enduring surface. It has the advantage of retaining the oil a longer time than a sandy surface does. A single treatment annually with a well chosen oils sufficient to keep such a limestone surface in very good condition.
Brick from Alluvial Clays.-The manufacture of brick from local clays is an industry of importance because of the local demands of a large population. The quality of the product is entirely satisfactory for the uses to which it is put, but is not such as to cause a demand from outside the locality. Moreover, most of the clay used here is of a grade which is found very generally distributed over the United States. Much brick for "facing" walls and for ornamental purposes is shipped in from other localities.
The chief source of brick clay is alluvium from the flood plains of the larger streams. As explained above, the mud of flood plains has settled from flood waters, and generally, therefore, occurs on top of the sand and gravel. As the surface of the latter is apt to be some at uneven, due mainly to the wash of local currents in the flood waters, the mud which coats the plain may be much deeper at some places than at others. It is also finer, less gritty, and more plastic at some places, because the water from which it settled was more stagnant. All or nearly all of the grit was dropped from suspension before reaching these places of the best clay.
Owing to these differences of depth and quality, the selection of a spot for a brickyard on the flood plain is a matter of importance. Usually it is done by actually testing the clay. Most of the yards are located near Cincinnati and Hamilton. At Delhi, on the Ohio, the clay is found satisfactory to a depth of fifteen feet, though a test boring to fifty feet showed little sand, but most of the clay below fifteen feet is too sandy for brick making. The clay used at most yards averages much less than fifteen feet in thickness.
All of the brick made from alluvium near Cincinnati are made by a "wet mud process," that is, the clay is mixed with water before being put into the molds. The bricks must then be dried before being burned. All are common red brick, and are used largely on the inside of walls, though sometimes the best are selected out to be used for facing.
In the Miami Valley, just north of Hamilton, alluvial clay has been much used in the way here described, but in the only plant operating at present the "dry process" is used. In this process the clay is first thoroughly mixed without addition of water, and then pressed into molds. A higher grade of brick is thus produced.
At Milldale (or Lattonia) brick of similar grade is being made on a large scale from the silts composing the terraces along the Licking.
Brick From the Surface Silt.-A smaller number of plants are making brick from the surface silt. These plants are located on the uplands, mainly on the flatter uplands where the surface silt has the character of the "white clay" described in chapter VI. Most of the yards are located on the line of the Cincinnati, Lebanon & Northern Railroad between Rossmoyne and Brecon. At the latter place the white clay is six or seven feet deep with a few stones near the base. For brick making the topmost four or five feet of the underlying till is also used. The number of stones increases with depth. Beyond the depth of ten or eleven feet front the surface, the number of stones is too great. The brick made from this clay are similar in quality to those made from the alluvium.
Shale Brick.-A plant in the west bluff of Mill Creek Valley in Cincinnati, and another in the bluff at Newport, Ky., have been making brick by a dry press process from the Eden shale, The shale is finely ground in a crusher and then firmly pressed into molds, generally with no other moisture than that which it contains when taken from the bank. The shale of the Eden group is of excellent quality for such use. It might well afford the basis of a large industry were it not for the interbedded limestone, and the popular preference at present for other styles of brick. The limestone has been successfully eliminated in the two plants mentioned. The thicker beds have been sold for building purposes, and the fragments from the thinner beds have been eliminated in the crushing process.
The brick thus made from shale is of high grade, having ample strength and a beautiful red color. It is used exclusively for facing. Styles come and go in brick as well as in clothing, and unfortunately for the shale brick industry in recent years, red pressed brick have not led the style. When they come into popular favor again it may be expected that the Eden shale will be more largely used.
Cupola Lining.-On the upland northeast of Delhi the surface silt is locally a dense clay rather than a silt. From several extensive pits this clay has long been dug and sold to foundries for lining cupolas. Although it is not commonly thought necessary to use a very particular grade of clay for this purpose, the clay from these pits has enjoyed great favor, and has sometimes been shipped to neighboring states. It is locally spoken of as fire clay, but chemical analysis shows that it does not differ much in constitution from the same formation elsewhere. The iron, lime, magnesia, and alkalis of clays constitute fluxes, that is, they make the clay soften at lower temperatures. The amount of such flux in this clay is too large for a fire clay.
Sand and gravel for structural purposes is widely distributed in this region, as might be expected where a great ice sheet came to an end by melting. Deposits are found in all the formations shown on the map as composed in whole or part of material laid down by glacial waters, and in addition to these, from the recent alluvium. These formations furnish material of all grades of coarseness, large cobble stones for paving, smaller pebbles for roofing, ballast, and concrete, and sand for mortar and cement.
From Deposits of the Illinoian Glacial Stage. - The oldest formation of this nature is the Illinoian outwash interbedded with till of the same epoch. It will be recalled that where these gravels are exposed at the edges of the Illinoian terrace, they are in large part consolidated to conglomerate. On this account, and because gravel is so much more available in other deposits, that of this age is not much used. The bank north of Coney Island, and some small private banks or pits are in this formation The large excavation by the Pennsylvania Railroad in the knoll one mile north of Milford, has been made to obtain filling. For this purpose gravel, sand, and bowlder clay have been taken without discrimination. The sand from this formation is likewise less used than that of later epochs. In general it seems to be less "sharp" and, therefore, less valuable for building purposes.. One large bank in this formation is in the east bluff of the Little Miami on the road to California and Mount Washington.
From Deposits of the Wisconsin Glacial Stage. - The great resource of sand and gravel is found in the terrace remnants of the valley trains of the Wisconsin stage. Probably not many localities in Ohio or adjacent states would compare in this respect with the Miami and Little Miami valleys. In the former, the Big Four Railroad owns a large area of terrace land at Valley Junction, and the Chesapeake & Ohio owns a similar area at Valley View. Both railroads operate large pits and ship the gravel for ballast to neighboring states. The Norfolk & Western Railway owns a large area in the Little Miami Valley south of Terrace Park, though a part of this is on terraces a little lower and younger than those of the Wisconsin stage. There are also large gravel pits at Loveland and Terrace Park.
Many large sand and gravel pits in this formation are owned and operated by companies which supply structural materials to Cincinnati and other cities. Some of these have installed crushers, washers, and screens for assorting the material. Such pits are distributed along the Little Miami from Loveland to Linwood (Cincinnati). Large operations of the same kind are carried on at Bellevue, Ky., at Sedamsville (Cincinnati), at Bond Hill (Cincinnati), and along the Miami between Miamitown and New Baltimore. Harrison, just west of this area, has very large deposits of gravel of this age which are being to some extent worked.
The kames of the same age at Camp Hageman contain a vast amount of good sand and gravel. One large pit has been opened and thoroughly equipped and is now shipping extensively to Cincinnati and other cities. Gravel has also been taken at various times from the kames south of Hamilton.
From Recent Alluvium.-Of operations in terraces younger and lower than the Wisconsin outwash, the most extensive is east of Trenton, near Miami River. The stones of the gravel here are rarely larger than two or three inches and a large amount of sand is obtained.
Sand for building purposes is also pumped from the bed of Ohio River and Mill Creek. Excellent sharp sand is thus obtained. At places, pumping may be carried on year after year, the supply being replenished during floods.
Characteristics of Molders' Sand.-The process of casting iron is essentially this: a "pattern" of the same size and shape as the iron casting to be made is embedded in sand closely packed. By a device not necessary to explain in detail, the upper half of the sand is lifted off and the pattern is removed. The upper half is then replaced on the lower, thus leaving a hollow interior, into which the melted metal is poured.
The sand for this purpose must be carefully chosen. Its essential quality is a tendency to pack and retain its form despite considerable jar. This must be accomplished with the sand almost (but not quite) dry, otherwise steam would form when the metal is poured in and the mold would be shattered. A small amount of moisture and therefore of steam is inevitable. An admixture of adhesive substance like clay would cause the sand to hold its shape, but if it filled the pores and prevented the escape of steam, the mold would still be shattered.
The characteristics of a molding sand, by virtue of which it packs and holds its shape and does not "blow" when the metal is poured in, are as follows: The grains should be angular. This causes them to interlock and thus to move over one another with difficulty. They should be of different size. The smaller ones occupy the pores between the larger. In this way the structure is made denser and stronger. A third feature is some kind of "bond" causing the grains to adhere slightly. If clay be present in sufficient amount to do this, it is apt to clog the pores, causing the mold to explode or "blow" when the metal is poured in, and the moisture is converted into steam. Much molders' sand, especially of the coarser grades, has a small amount of iron oxide coating the grains and causing some adhesion. The amount required does not seriously clog the pores and it is very efficient as a bond.
Sand From the Loess.-The finer grades of molders' sand are obtained from the loess. It is dug out in large quantities from the bluffs back of Covington, Newport, and Bellevue, Ky., likewise from a large deposit twenty or more feet deep at the foot of the bluff back of Delhi. The topmost two or three feet are discarded because weathered in part to clay. Of the loess beneath that, some is not suited to use as molding sand. That which is so used is still further classified as to coarseness. The loess is used in making relatively small castings. It is shipped not only throughout Ohio, Indiana, and Kentucky, but frequently to more remote states.
Loess is also used in other ways; sometimes to give body to dynamite; sometimes to serve a similar purpose in commercial fertilizers.
Sand Beneath the Surface Silt.-Coarser grades of molders sand are obtained at various places on the uplands near Cincinnati, just beneath the surface silt. One such deposit near Cold Spring, Ky., is about fifteen feet thick. It is a quartz sand containing a small amount of iron oxide as bond. Similar deposits are being worked on the upland northeast of Delhi and east of North Bend. The last named deposit is associated with much gravel, five-sixths of whose pebbles are of chert and quartzite, the remainder being vein quartz and various igneous rocks.
Sand From the Wisconsin Outwash-Another source of molders' sand is the glacial outwash of Wisconsin age. Whole fields near Overpeck, north of Hamilton, are found underlain by such sand. It is found just beneath the soil in a bed rarely exceeding three feet in depth. Beneath this is clean sand suitable for building purposes. Some thousands of tons of this molders' sand have been shipped away in past years. Many acres have thus been stripped. The land after stripping is again farmed. A deposit, in every way similar to this, was worked for many years just south of Schenck's Station, on the C. H. D. Railway.
Deposits of this character show something of the origin of these coarser grades of molders' sand. They differ in no important respect from the clean sharp builders' sand beneath, except in the matter of the iron oxide which makes the bond. Wash this out and the sand which remains is indistinguishable from that which lies beneath. It is plain that the sand as originally washed out from the glacier and deposited, was common sharp sand like the deeper beds at present.. Being of glacial origin a part of its grains were of the dark minerals containing iron. These decayed, giving rise to iron oxide. At the same time some of the clay from the soil above was washed down into the sand. Thus the molders' sand has progressively thickened at the expense of the clean sand below. The process is too slow to be of economic importance in historic time.
Surface and Subsoil Distinguished.-Soil is the surface portion of the mantle rock which is directly concerned in the support of vegetation. Generally a distinction is made between top soil and subsoil. The former, generally less than a foot in thickness, is commonly (though not always) darker and of finer grain. The contrast may not be sharp, and generally no exact plane of separation can be pointed out, but in many areas the distinction is sufficiently sharp so that the plowing up of an additional inch or two inches changes the character of. the surface soil very decidedly for better or worse.
Constituents of Soils.-The darkness of the top soil is due in part to the more complete oxidation of iron, and in large part to decomposing or decomposed vegetation called humus. This is one of the essential constituents of soils. Within the limits of ordinary agricultural soils, the more humus the better. It is always in danger of being too much reduced. In nature, without man, each generation of vegetation dies down and forms humus for later generations. When crops are cut and removed this order of nature is disturbed and the soil must be artificially fertilized.
It is not to be understood that humus is the only constituent of soils which is liable to depletion, or that fertilizers are added simply to restore this. There are many things in soils which are necessary to plant life, but most of them are sufficiently abundant so that their need is rarely felt. The three things most liable to depletion are nitrates (usually contained in humus), potash, and phosphate. Since these must so frequently be added, they are commonly regarded as the elements of fertility.
In recent years much has been learned concerning the importance of the physical condition of soils. Fertility is now known to be quite as dependent on physical condition as on chemical composition. Both are indispensable.
Functions of Subsoil.-While chemical compounds (plant food) are contributed to crops chiefly by the surface soil, they are derived in part also from the subsoil, being carried up in solution by ground water which rises from the water table by capillary attraction. It is one of the functions of the subsoil, therefore, to contribute food to the growing plant, but the most important function of the subsoil lies in its relation to the water itself. It must allow it to pass downward when there is too much at the surface, and must lift it again by capillarity when the surface is too dry. A subsoil which is right for hills in which the water table is deep would not be right for a broad flat bottom land where the water table is near the surface. If the broad bottom lands of the Miami Valley had a dense clay subsoil instead of the sand and gravel which they have, the surface would remain wet and the soil unworkable a long time after heavy rains; but if their porous subsoil were transferred to the hilltops, the water table would sink so low that crops could not survive a drought.
Soils Classified as to Origin.-Soils are either residual or transported. Residual soils are formed by the decay of the underlying rock. Hence they are also called soils formed in place. In a good section all gradations may be seen between the solid rock below and the fine soil above. (See Fig. 56). Those formed by the decay of limestone and calcareous shale (as in the Blue Grass region) are almost always fertile; those on non-calcareous shales less so, and those on sandstone barren unless other elements have in some way been mixed in. Many uplands in eastern Ohio and Kentucky have soils made from sandstone. Igneous rocks may yield either good or poor soils. Those with the largest proportions of quartz (generally light colored rocks) are least apt to produce good soils. The darker rocks contain more decomposable minerals and yield more clay, making better soils both chemically and physically.
Transported soils may be laid down by water, wind, or ice. All three kinds, as well as residual soils, are represented in this area. All transported soils have this in common: they are made of materials gathered from many localities; hence they are apt to be heterogeneous in character. The chances of being fertile are thus greatly increased, though not all transported soils are fertile.
It will readily be seen that on steep slopes the mere process of creeping" plays a large part in mixing soils. Especially is this true where the rocks at different levels are of different kinds. In such cases it is no longer true that each kind of rock is overlain merely by its own products of decay. The soil near the base of the slope may be a mixture of the soils formed on various kinds of rock. . Such are not transported soils in the sense of water-laid, wind-laid, or ice-laid sediments. They are known as colluvial soils. It is not necessary to distinguish them from residual soils in this area.
The soils of this region may be classified according to their derivations from the following formations: (1) the bed rock (residual soil), (2) the surface silt and loess (soils due to wind transportation), (3) the bowlder clay of the Wisconsin stage (soils due to ice transportation), and (4) the alluvium (soils due to water transportation).
Residual Soils.-Where the Pleistocene formations named are absent, the soil is formed by the decomposition of the limestones and shales. Such soils are, therefore, in the main, limited to the steeper slopes where the Pleistocene formations either failed to come to rest or have been subsequently washed away. Residual soils are found locally on the bluffs of the Ohio, Miami, and other great valleys and on the sides of the steep valleys by which these bluffs are at places dissected. These are the places where the bowlder clay and surface silt, if ever deposited, have been largely washed away. It may readily be inferred that the soil on such slopes is thin, for it tends constantly to wash down. This is especially true since the cutting away of the forests from much of this hilly land. Except for their thinness, these soils are fertile, and enduring. They are of the same general character as the soils of the famous Blue Grass region of Kentucky. Their color is dark yellow or ruddy, and they may be further darkened by decaying vegetation. At many places they contain slabs of limestone derived either from close at hand or. by "creep" from the higher slopes. Wherever these residual soils have sufficient depth they are well adapted to general farming.
Surface Silt and Loess Soils.-The mantle of silt or silty clay, which covers practically all of the older till sheet, is the most important soil maker in the southern half of the area. The till of Illinoian age has no importance in this respect, being almost entirely covered. This silt sheet derives its colloquial name "white clay" (used from Illinois to Ohio) from the soil which it produces on nearly flat uplands where the subsoil is not well drained and aerated. Under these circumstances the color of the surface soil is a pale yellowish or gray. A common characteristic of such tracts is a large number of holes and mounds of the common crayfish. Hence the common term "crawfish lands" in southern Indiana and Ohio generally applies to uplands whose soil is derived from the surface silt. The term "slash lands," used in Indiana, designates the same thing. Where humus is abundant the color of the soil becomes a darker gray or even brown. It is generally mellow and free from clods where drainage is fair and humus not deficient. Such is generally the case within this area. Where it covers broad flat uplands, as in some counties of southern Indiana and Ohio, the drainage is poor, and humus generally deficient. The soil is then very light in color and intractable. If plowed too wet it forms clods like sundried bricks. So far as this area is concerned the soil on the surface silt may be called a "silt loam."(See note 35). It is fair for general crops and generally good for. wheat; likewise for fruits.
A highly important soil due to wind transportation is represented in this area by that which is formed on the true loess on the southern bluffs of the Ohio. It is a mealy loam of excellent physical properties. In this area it covers only a narrow strip of hills. Where it covers broad areas, as in Iowa, Missouri, Illinois, and eastern Nebraska, it forms the basis of one of the chief agricultural soils of the United States.
Soils on the Bowlder Clay.-The soil formed on the younger till sheet is in general a medium loam, locally a sandy loam. This character is determined by the composition of the till. Being derived from a formation which is itself derived chiefly from the underlying limestone and shale, it is not unlike the residual soil in ultimate constitution. Over most of the area, stones are rare in the topmost two or three feet of the younger till and hence in the soil. At places, however, this stoneless zone is absent, and spots of gravelly or stony soil appear. In contrast with the gray color of the soil on the surface silt to the south, this soil has a yellowish color, with here and there brown or even black patches. These give a clouded appearance to the surface in almost any wide outlook over plowed fields. Another contrast between this soil and that farther south is, in the matter of destructive washing. Gullies are not unknown on the Wisconsin till. In a few places the washing of the soil is serious. But there is nothing like the wholesale wasting of soils by gullying which is witnessed on the older formations. (See Pl. Xl-B.) In general fertility this soil is decidedly superior to that found farther south on the older Pleistocene formations. Farmers on both sides of the border line speak familiarly of this contrast. A line traced between the better soils on the north and the poorer soils on the south by the sole criterion of reputation for fertility, would nowhere deviate more than a mile or two from the edge of the younger drift sheet. This reputation is reflected in the prices paid for land. A difference of twenty-five to fifty per cent in favor of the till soils to the north is not uncommon. Mason, on the relatively flat uplands covered by the younger drift, is the center of a prosperous canning industry. With a you similar topography, the vicinity of Hazelwood and Brecon is decidedly inferior as a farming section.
Alluvial Soils. -Probably the most fertile and highest priced farms in the area are found on the terraces and flood plains of the broad valleys. Many farms on these alluvial soils have been bought at $150 to $200 per acre. From the origin of alluvium it is plain that soils formed upon it may have any texture, from gravel at one extreme, to dense gummy clay at the other. The broad valleys of this area have a very large proportion of medium loams. For practical purposes these alluvial soils must be divided into two classes those which are liable to flooding and those which are not. In genera this corresponds to the division between flood plains and terraces. Under this head of alluvial terraces the broad terraces of the Illinoian glacial epoch in Mill Creek Valley and elsewhere are not included. These are not only formed in part of bowlder clay, but covered with the surface silt which is the basis of their soils.
The largest areas of alluvial terrace are found in the Miami Valley. The most extensive tract is in the "Hickory Flats" stretching from Sevenmile to Trenton and south to Overpeck. This is one of the best farming districts in the Miami Valley, which is widely known for its beautiful farms. At the surface are a few feet of loam. The deeper subsoil is everywhere of sand and gravel. On account of the wide extent of nearly flat surface at a low level, the water table is sufficiently near the surface so that the soil is not unduly dried out despite the very porous nature of the subsoil. Similar soil conditions are found in parts of Mill Creek Valley and in the New Haven trough where the name "Hickory Flats" is likewise used.
Over considerable areas the flood plain soils are quite as fertile as these terrace soils. Venice is the center of such a section. It was generally believed to be above flood level, but it was submerged by the flood of March, 1913. As is the habit of floods on bottom lands, there were local currents which scoured channels in the fertile loam and cut deep into the gravels below. Locally such scour reached a depth of twenty feet. Elsewhere fields were buried by shoals of sand and gravel, sometimes to a depth of four or five feet. Such local disasters are very impressive, but they affect only a small fraction of the total area of alluvial soils. They should not be allowed to divert attention from the larger fact that where the flood moved slowly or rested quietly it was depositing fertile silt. In other words, it was engaged in the same process by which the fertile bottom lands were originally made. In this way, the resources of fertility for the future are stored up.
