CHATTANOOGA ATLAS SHEET.

DESCRIPTION.

GEOGRAPHY. bluff. At Chattanooga the river leaves the broad from any high land that could yield coarse sedi­ shales with some beds of sandstone. Still further General relations. The Chattanooga atlas sheet Appalachian valley, and sweeping past the foot of ments. east, in White Oak mountain, the formation attains is bounded by the parallels 35° and 35° 30', and Lookout mountain enters the narrow canyon carved Connasduga shale. This formation is composed a thickness of 1,000 feet, of which the lower 800 the meridians 85° and 85° 30'. It embraces, there­ across Walden ridge. With steep wooded slopes at the base of thin limestones interbedded with are made up of hard brown sandstone interbed­ fore, a quarter of a square degree of the earth's rising from the water's edge and surmounted, a shales, in the middle of yellow or greenish clay ded with sandy shale. The upper portion consists surface. Its dimensions are 34'5 miles from north thousand feet above, by vertical cliffs of gray sand­ shales, and at the top of blue seamy limestone or of sandy shale with a few calcareous beds. The to south, and -28'2 miles from east to west, and it stone, the gorge affords some of the most pictur­ calcareous shales. Some of the thin beds of lime­ formation is named from Rockwood, Tennessee. it contains 974'64 square miles. The adjacent esque scenery to be found in the southern Appa­ stone, especially those near the lower part of the It is of great practical importance on account of atlas sheets are, on the north, Pikeville, on the lachians. formation, have a peculiar oolitic structure, being the beds of red fossil iron ore which it usually con­ east, Cleveland, on the south, Kinggold, and on the Compared with its upper valley, the gorge of the made up of rounded or flattened grains about a tains. These are described under the head Min­ west, Sewanee. The sheet lies wholly within the Tennessee below Chattanooga is extremely young tenth of an inch in diameter. This oolitic lime­ eral Resources. and there is evidence that it has been occupied by stone is sometimes absent. The boundary between State of Tennessee, the southern limit being within DEVONIAN ROCKS. about a mile of the Tennessee-Georgia line. It the present river but a short time. Until recent the Rome and Connasauga then becomes very in­ embraces portions of Bledsoe, Rhea, Sequatchie, geologic ages the Tennessee probably continued definite and their separation difficult. The same Chattanooga black shale. Overlying the Rock- Marion, Hamilton, and James counties. southward in the broad Appalachian valley di­ is true when the upper part of the Rome also con­ wood formation is a thin stratum of shale which Topography. The country included within the rectly to the Gulf of Mexico. Since it was diverted tains beds of lime, as is sometimes the case. The appears to represent the whole of the deposition atlas sheet presents several widely different types to its present course it has lowered its bed only thickness of the Connasauga shale probably varies which took place in this region during the De­ of surface. The differences are due jointly to the about 250 feet, this being the height of the divide between 1,500 and 2,500 feet, but on account of vonian period. Typical exposures of this shale character of the underlying rock and to the geo­ which separates its waters from those still flowing the great contortions which the beds have suffered, appear in the north end of Cameron hill within the logic structure the relation of the strata to the southward. the same uncertainty attaches to their measurement city limits of Chattanooga, from which locality it surface. This connection between the geology and Crossing the southeastern corner of the sheet in as to that of the two older formations. The forma­ takes its name. the topographic features will be explained later. a direction parallel to the edge of Walden ridge is tion takes its name from the Connasauga valley, in The Chattanooga black shale has a remarkably Beginning in the northwest corner of the sheet White Oak mountain, a sharp ridge steep on its Georgia, on the Dalton sheet. uniform character wherever seen within the limits and passing to the southeast, the following distinct western side and sloping gently to the east, with The Cambrian formations occupy a compara­ of the atlas sheet, and for a long distance on either areas may be noted: (1) the Cumberland plateau, an elevation from 1,300 to 1,500 feet above sea tively small portion of the area of the Chattanooga side north and south. It varies in thickness from (2) the Sequatchie valley, (3) Walden ridge, (4) level. East of White Oak mountain are numerous sheet. Two narrow strips occur near the center of 10 to 25 feet. The upper portion of the shale, the Tennessee valley, (5) White Oak mountain. ridges, in a general way parallel with it but lower the Tennessee valley, and a somewhat broader belt three or four feet thick, is usually dark gray in A small portion only of the Cumberland plateau, and less regular. Grindstone mountain, however, crosses the extreme southeastern corner of the color and often carries a layer of round concre­ about 85 square miles, is embraced within the lim­ has an elevation somewhat greater, and with its sheet. The latter is limited by faults upon both tions about an inch in diameter. The remainder its of the sheet. The general surface is level or level top and steep sides it forms a small isolated sides and consists wholly of the two lower forma­ of the formation is jet black, from an abundance of rolling, elevated approximately 2,100 feet above plateau or mesa in all respects, except in its limited tions, the Apison and Rome. carbonaceous matter, and when freshly broken it sea level. The drainage is by streams flowing extent, similar to the Cumberland plateau in the emits a strong odor like petroleum. northwest to the Cumberland river and southeast western portion of the sheet. SILURIAN ROCKS. This shale, on account of its distinctive and strik­ to the Sequatchie. These streams have rapid fall Knox dolomite. The lowest division of the Si­ ing appearance, has attracted much attention from and the larger ones have cut deep canyons several STRATIGRAPHY. lurian, the Knox dolomite, consists of from 3,000 miners, and has been prospected in many places for miles back from the edge of the plateau. to 3,500 feet of massively bedded and somewhat coal and various ores, especially silver and copper. All the rocks appearing at the surface within Toward the southeast the plateau is terminated crystalline magnesian limestone. This limestone, Such exploitation, however, has always been at­ by an abrupt escarpment, trending 1ST. 30° E. and the limits of the Chattanooga atlas sheet are of or more properly dolomite, contains a large amount tended by failure, since the shale contains nothing sedimentary origin, that is, they were deposited by forming the western edge of the Sequatchie valley. of silica in the form of nodules and layers of chert of present economic importance. Although it con­ water. The materials of which they are composed On the eastern side of the valley is an escarpment, or flint. Upon weathering, that part of the rock tains a large proportion of carbonaceous matter were originally mud, sand and pebbles derived similar, but less broken by stream channels and which consists of the carbonates of lime and mag­ which burns when it is placed in a hot fire, the from the waste of some older rock, or the remains somewhat higher than that on the west. The width nesia is dissolved, leaving behind the chert, usually amount is not sufficient to constitute a fuel, and no of the valley between these two parallel escarp­ of plants and animals which lived while the strata imbedded in red clay. This residual material cov­ true coal is ever found associated with the shale. ments is about four miles and its general surface were being laid down. Thus some of the great ers the surface to great depths and the dolomite Small concretions of iron pyrites, which it often is between 700 and 800 feet above sea level, or beds of limestone were formed largely from the itself is seldom seen except in the channels of the carries, have given rise to the commonly accepted shells of various sea animals, and the beds of coal 1,300 feet below the adjacent plateau. larger streams. but wholly erroneous belief that the shale contains East of the Sequatchie valley is Walden ridge. are the remains of a luxuriant vegetation which The Knox dolomite comes to the surface in a valuable ores. The formation is of economic im­ This is not properly a ridge but rather a plateau covered low, swampy shores. belt about two miles wide through the center of portance only as a starting point in prospecting the Sequatchie valley and occupies the greater part for the red fossil iron ore which occurs below it which resembles in many respects the Cumberland CAMBRIAN ROCKS, plateau. Its area within the sheet is about 330 of the Tennessee valley between Walden ridge and and at a uniform distance, over considerable areas. square miles, or one-third that of the entire sheet. Apison shale. The oldest rocks exposed within White Oak mountain. In both valleys its outcrops The surface slopes gently toward the southeast the limits of the sheet consist of slightly sandy or are marked by the characteristic low, rounded, CARBONIFEROUS ROCKS. from 2,200 feet above sea level on the western clay shales named from their typical development chert hills, which rise from 300 to 400 feet above fort Payne chert. This formation consists of edge to 1,700 on the eastern. The drainage is at Apison near the southeastern corner of the sheet. the level of the streams. from 50 to 200 feet of very siliceous limestone. At wholly toward the southeast. A large number of Their most striking peculiarity is the brilliant col­ Chickamauga limestone. The next formation the base, resting on the Chattanooga black shale, streams head near the western side, frequently oring which they display in sharply contrasted is the Chickamauga limestone, which occupies a are usually heavy beds of chert with only a small within a few hundred yards of the escarpment, bands of red, purple, green and yellow. The thick­ broad, continuous belt along the eastern side of amount of limestone or greenish calcareous shale. and, flowing southeast in gradually deepening ness of the formation is not known, since it is the Sequatchie valley and a much narrower one, In the western part of the sheet the line increases channels, emerge into the Tennessee valley from always limited on one side by a fault, but at least not entirely continuous, along the western side. toward the top of the formation and gradually re­ deep rocky gorges. As the streams debouch upon 1,000 feet are exposed at its type locality. The formation is here a pure, blue, thin bedded placing the chert it passes without an abrupt tran­ the valley their descent is less rapid so that they A bed of gray siliceous limestone sometimes limestone, about 1,000 feet in thickness. It ap­ sition into the Bangor limestone above. It is there are able to carry less sediment, hence a part of the occurs between this and the succeeding formation, pears again on the eastern side of Walden ridge about 200 feet thick. In White Oak mountain and material eroded from the gorges is deposited in a but though found both north and south of this with much the same character as in the Sequatchie eastward the lower part of the formation is com­ kind of delta around their mouths. Since these de­ region it does not occur within the limits of this valley. East of Chattanooga and in the South posed of heavy beds of chert, while the upper part posits are composed wholly of coarse sand, gravel sheet. Chickamauga valley are large exposures of the for­ contains coarse cherty sandstones which become and boulders they are quite porous and most of Home formation. Next above the Apison shale mation, where it has a thickness of about 1,600 feet porous by the solution of the calcareous matter the streams wholly or in part disappear from the are the sandstones and shales of the Rome forma­ and contains a considerable amount of earthy im­ they originally contained. The chert of this for­ surface for short distances. Toward the southern tion. They are between 3,000 and 4,000 feet in purity. Along the western base of White Oak mation is readily distinguished from that of the edge of the sheet Walden ridge is cut through by thickness, but on account of the folding and crump­ mountain is another broad belt showing a still Knox dolomite by the great number of fossils the Tennessee river, which at Chattanooga turns ling which the strata have suffered it is impossible further increase in thickness to about 2,200 feet, which it contains. It is often made up of a mass westward almost as right angles to its upper course. to obtain accurate measurements. The lower part and also a greater proportion of earthy material, of crinoid stems imbedded in a siliceous cement; East of Walden ridge is the valley of the Ten­ of the formation is composed of alternating layers especially in the upper part of the formation. The on weathering, the cement remains a porous chert nessee river, a portion of the great Appalachian of sandstone and shale. Passing upward the pro­ Chickamauga limestone takes its name from the filled with the fossil impressions. In some cases valley which extends toward the northeast through portion of shale gradually increases, so that toward valley of Chickamauga creek, on the Chattanooga the fossils alone are silicified so that they remain Virginia and Maryland into Pennsylvania and the top only a few thin siliceous beds occur, which and Ringgold sheets, where it is typically de­ in the soil after the solution of the calcareous toward the southwest through Georgia into Ala­ can scarcely be called sandstone. The shales are veloped. cement. The formation occurs in a narrow strip on bama. The area of the portion embraced within usually brown or dark olive-green, while the sand­ Rockwood formation. The Rockwood forma­ the eastern side of the Sequatchie valley, usually the atlas sheet is about 440 square miles. The stone beds are reddish brown or purple, with oc­ tion, which is the highest division of the Silurian forming, with the Rockwood shale, a narrow ridge elevation of the Tennessee river is between 670 casional layers of white quartzite. The sandstone in this region, varies widely in character and thick­ parallel to the mountain escarpments. Along the and 700 feet above sea level, and the general sur­ beds show ripple-marks and other signs of having ness within the limits of the sheet. It forms a nar­ eastern base of Walden ridge the formation occu­ face of the valley is a little higher, but many hills been deposited in shallow water, but the water was row strip along the eastern side of the Sequatchie pies somewhat larger areas though it is not entirely and irregular ridges rise two or three hundred feet evidently growing deeper during their deposition, valley, with a thickness of about 200 feet, and is continuous across the sheet. It forms the greater above the river. The actual flood-plain or bottom and the succeeding formation contains limestone composed of calcareous shales and some beds of part of Cameron hill in Chattanooga and the gentle is nowhere extensive, and on one side or the other and calcareous shale, which must have been formed blue limestone. On the eastern side of Walden eastward slopes of White Oak mountain. The for­ the river usually washes the base of a steep, rocky on a comparatively deep sea bottom and remote ridge it is 300 feet thick, and consists of calcareous mation name is taken from Fort Payne, Alabama. Floyd shale. As before stated, the chert, on These two formations, the Lookout and Walden region. West of this the strata are nearly hori­ relation of coal beds in the different parts of the the western portion of the sheet, passes upward sandstones, constitute the productive coal meas­ zontal though broad undulations can be detected field. directly into the Bangor limestone, but east of ures. The position and thickness of the various by careful measurements. On the eastern side of The vertical distance from the top of the Ban­ White Oak mountain another formation, the Floyd beds of coal will be described under the head of the valley the strata dip beneath Walden ridge at gor limestone to the top of the conglomerate, that shale, comes in between them. This consists of Mineral Resources. angles varying from 15° to 20°; on the western is, the thickness of the Lookout sandstone, varies from 600 to 850 feet of variable sediments, for the At the close of the Carboniferous period this side of the valley they are much steeper, being gen­ between 450 and 550 feet. Wherever the rocks most part carbonaceous shales, containing local region was elevated permanently above sea level, erally vertical or overturned. Along the western are w^ell exposed, at least three beds of coal are seen beds of fine grained, flaggy sandstone, and also so that the constructive process of deposition was side of the valley there is a fault, and this, as ex­ between these limits and in some places as many some beds of blue limestone with nodules of chert. stopped and the destructive process of erosion was plained above, is the further result of the action as six. One bed immediately below the conglom­ These calcareous portions are highly fossiliferous, begun. of those compressing forces which produced the erate, or heavy sandstone, is fairly constant in posi­ though the black shales are generally quite barren STRUCTURE. fold. In consequence of this fault some of the for­ tion though it varies considerably in thickness. of organic remains. Definition of terms. As the materials forming mations which- occur on the eastern sider of the From a few inches at the northern edge of the Bangor limestone. The Bangor limestone is the rocks of this region were deposited upon the valley and which should occur on the western side sheet it increases southward to three feet or more, from 800 to 1,000 feet thick in the Sequatchie val­ sea bottom, they must originally have been in are concealed by other formations thrust across and is worked at the Daisy, ^Etna and McNab ley and on the eastern side of Walden ridge, where nearly horizontal layers. At present, however, the their broken edges. Thus the Chickamauga lime­ mines. Below this the Dade coal, which at the it forms the lower portion of the mountain slopes. beds are not usually horizontal, but are inclined to stone and Knox dolomite come into contact with southern edge of the sheet has a thickness of about East of White Oak mountain it is only 600 feet the surface at various angles. This is the result the Bangor limestone, while intervening formations, three feet and is worked principally at the Dade thick, resting on the Floyd shale, and only a single of compression in a northwest and southeast direc­ the Fort Payne chert, Chattanooga black shale and mines in Georgia, may be represented by one of small area has escaped erosion, though it doubtless tion, by which they have been bent into a series Rockwood shale, are concealed. This is the reason the thinner beds seen in the sections further north. formed a continuous sheet over the whole of this of arches and troughs. In describing these folded that the red fossil iron ore of the Rockwood for­ Of the remaining lower beds only one other is region, and originally may have extended some strata the term syncline is applied to the down­ mation is not found along the western side of the worked, namely, the lowest in the series, which is distance farther eastward. The limestone shows ward bending troughs and anticline to the upward valley. about 320 feet below the top of the conglomerate. with unmistakable clearness the mode of its for­ bending arches. A synclinal axis is a line run­ The axis of the Walden ridge syncline is con­ It varies in thickness within distances of a few hun­ mation. It is in many cases composed almost en­ ning lengthwise of the synclinal trough, at every siderably east of the central line of the plateau. dred feet from a mere streak to three or four feet. tirely of fragments of crinoids together with the point occupying its lowest part, toward which the Thus there is a slight easterly dip from the western In the first 125 feet above the conglomerate is calcareous coverings of other sea animals which rocks dip on either side. An anticlinal axis is edge almost entirely across to the eastern escarp­ a group of from two to four coal beds, at least one died and left their remains on the sea bottom. a line which occupies at every point the highest ment. This fact has great practical importance of which is generally workable. Exact correla­ It is probable that the lower portion of the portion of the anticlinal arch, and away from which since it insures easy drainage of coal mines and tions of the beds within this group have not been Bangor limestone on the western part of the sheet the rocks dip on either side. These axes may be hence economical mining. made, and it is quite probable that a single bed in and the Floyd shale on the eastern part were de­ horizontal or inclined. Their departure from the Between Chattanooga and the edge of Walden one part of the field may be separated by shale posited at the same time, the former in a compar­ horizontal is called the pitch of the axis and is ridge there are three small folds shown in section and sandstone layers into two or three in another atively deep sea and the latter near the shore where usually but a few degrees. In addition to the C C of the structure section sheet. Of these the part. This is the horizon at which occurs the coal the supply of mud and sand was abundant. Al­ folding, and as a result of the continued action of western extends southward, forming Lookout val­ so extensively worked at Tracy city and other though they may be of the same age, the rocks the same forces which produced it, the strata along ley upon the Ringgold sheet, and northward to points west of Sequatchie valley. A bed occurs differ so widely in character that they are given certain lines have been fractured, and the rocks Falling Waters creek, but almost entirely disap­ in several of the sections at a quite uniform dis­ distinct formation names. The name of the lime­ have been thrust in different directions on opposite pears before reaching the line of section B B. This tance of from 250 to 275 feet above the conglom­ stone is taken from Bangor, Alabama, and that of sides of the fracture: this is termed a fault. folded belt is cut off on the eastern side by a fault erate and is worked at the Daisy and JEtna mines. the shale from Floyd county, Georgia. Structure sections. The three sections on the which passes through the east side of Cameron Finally the Richland coal, 630 feet above the con­ The presence of the Floyd shale on the eastern structure sheet represent the strata as they would hill in Chattanooga and extends northward a short glomerate, is worked near Dayton, just off the and its absence from the western portion of the appear in the sides of a deep trench cut across the distance from the edge of the plateau to about north edge of the sheet. The rocks containing the sheet, together with the changes already noted country. Their position with reference to the map Retro. Beyond this a narrow syncline extends Richland coal have been quite generally eroded, in the lithologic character of the Rockwood and is on the line at the upper edge of the blank strip. to the edge of the sheet, forming Lone mountain so that the workable area of the bed is not so Chickamauga, indicate that during their deposi­ The vertical and horizontal scales are the same, so and the ridge east of Coulterville. This narrow great as that of beds lower in the series. This coal tion the land, from which the sediments were de­ that the elevations represented in the profile are syncline is separated from Walden ridge by a is found only in the deeper parts of the Walden rived, was toward the southeast while the deep not exaggerated, but show the actual form and faulted anticline which forms the valley of Sale ridge syncline and in isolated hills rising above the sea was toward the northwest. slope of the land. These sections represent the creek. Section A A shows the manner in which main floor of conglomerate. The same limitation Lookout sandstone. At the close of the period structure, as it is inferred from the position of the the strata of Lone mountain have been thrust over in area is applicable to the next lower workable occupied by the deposition of the Bangor limestone strata observed at the surface. On the scale of upon the eastern edge of the Walden ridge syn­ bed, the ^Etna coal, though in a lesser degree. there was an uplift of the sea bottom, so that the the map they can not represent the minute details cline. In conclusion, without attempting strict correla­ water became shallow over a wide area while an of structure; they are therefore somewhat general­ The Tennessee valley is developed for the most tion of individual beds, the coals of the Walden abundant supply of mud and sand was washed in ized from the dips observed in a belt a few miles part upon the Knox dolomite, which lies in broad formation may be grouped at three horizons, at from the adjoining land. These conditions were in width along the line of the section. and rather gentle folds. Two sharp anticlines any one of which workable coal is likely to be unfavorable for the animals whose remains are so Faults are represented on the map by a heavy bring the underlying Cambrian rocks to the sur­ found. The first is within 120 feet above the con­ abundant in the preceding formation, and instead solid or broken line, and in the sections by a line face in long narrow strips of nearly vertical strata, glomerate and contains the beds worked over the of limestone a great mass of shale and sandstone whose inclination shows the probable dip of the while two strips of nearly horizontal Chickamauga widest area. The second horizon is from 250 to was deposited. The surface also stood above sea fault plane, the arrows indicating the direction in limestone occupy portions of the synclines. The 275 feet above the conglomerate and contains the level at various times, long enough at least for the which the strata have been moved on its opposite one between Chattanooga and Missionary ridge is beds worked at ^Etna and Daisy. The third is growth of the luxuriant vegetation which formed sides. bounded on the east by a fault, on which, as shown about 630 feet above the conglomerate and con­ the coal beds. Relation of topography to sfructure. The most in section C C, the dolomite forming the ridge has tains the Richland coal, but is restricted in area The Lookout sandstone includes 450 to 550 feet prominent structural as well as topographic feature been thrust across the overturned edge of the syn­ on account of erosion. of conglomerate, thin bedded sandstone, sand and upon the sheet is Walden ridge. It will be seen cline. All the coals of this region are bituminous, and clay shales, and coal. Its upper limit is at the top from the sections that the nearly horizontal strata Crossing the southeast corner of the sheet is a all so far tested are well suited for coking. A of a heavy bed of conglomerate or coarse sandstone which underlie this plateau dip gently away from fault which brings the oldest rocks of the region good quality of coke is made at Daisy, Rathburn from 25 to 75 feet in thickness, which forms the the edges toward the middle, forming thus a broad against the youngest. The displacement along this and Dayton. principal cliff about the edge of Lookout moun­ shallow trough; this is a typical synclinal moun­ line is much greater than in the faults further west, Iron ore. Two varieties of iron ore, which dif­ tain, south of Chattanooga and in the escarpments tain. In Sequatchie valley the strata are more being fully 12,000 feet. This motion has not fer widely in appearance and in modes of occur­ of Walden ridge and the Cumberland plateau. In steeply inclined and dip away from the middle usually taken place upon a single plane, but is rence, are found on the Chattanooga sheet. They the eastern part of the sheet the formation occu­ toward the sides; this is a typical anticlinal valley. distributed among several fault planes within a are hematite, or red fossil ore, and limonite, or pies but a single small area, capping Grindstone East of Walden ridge, in the Tennessee valley, narrow belt in which the rocks are greatly con­ brown ore. mountain, although it is probable that, like the also, a general arching of the strata is observed, torted and crushed. Hematite. The red fossil ore is associated with other carboniferous formations already described, though with less regularity than in the anticline rocks of the Rockwood formation and is very sim­ it once extended across the intervening region in of Sequatchie valley. In White Oak mountain the MINERAL RESOURCES. ilar to the ore occurring at the same horizon in a sheet continuous with that upon Lookout moun­ strata form a deep and narrow syncline, though it The mineral resources of the Chattanooga sheet such widely separated localities as Wisconsin, New tain. is the western edge of the trough which makes the consist of coal, iron ore, limestone, building and York and Alabama. It is a regularly stratified Walden sandstone. The Walden sandstone in­ mountain through the greater part of its length. road stone, and brick and tile clay. bed, retaining a constant thickness and definite re­ cludes all the rocks lying above the Lookout con­ Thus there is an intimate connection between Coal. The productive coal-bearing formations, lation to other strata of the formation over con­ glomerate. Its sandstones, shales and coal beds the structure and the present topography. The consisting of the Lookout and. Walden sandstones, siderable areas. Like any other rock stratum, how­ were deposited under conditions very similar to surface has been fashioned by the streams which occupy the surface of the Cumberland plateau and ever, it is not absolutely constant, so that, while those which prevailed during the deposition of the flow upon it, and the action of the streams has been Walden ridge. They have an area within the atlas the map indicates within narrow limits the areas preceding formation. The conditions, however, controlled by the position of the hard and soft sheet of about 400 square miles, and contain from within which the ore may occur, careful examina­ changed less frequently and were somewhat more layers of rock. The valleys in general are upon one to three beds of workable coal. tion is required to determine whether at any par­ favorable for the accumulation of coal. What the anticlinal arches, and the mountains are formed by The accompanying vertical sections on the co­ ticular locality its quantity and quality are such original thickness of the Walden sandstone may synclinal troughs. This result has been brought lumnar section sheet show the position and thick­ as to make it commercially valuable. have been can not now be determined, but it is about by the more rapid erosion of the.hard beds ness of the various coal beds. The sections are The proportion of iron in the ore usually de­ certain that much of the formation has been re­ at the tops of the arches than in the bottoms of not generalized, but each represents the actual creases with distance from the surface, and at moved by erosion. It is confined to the western the troughs. The streams must originally have measurements made at a single locality. It will considerable depths it becomes simply a more or part of the sheet, forming the surface of Walden flowed in the synclines, but they have gradually be seen that the beds vary considerably in num­ less ferruginous limestone. The decrease down­ ridge, from which it is named, and of the Cumber­ transferred their channels to the axes of the anti­ ber, position and thickness from one part of the ward in the proportion of iron is due to the fact land plateau. Its greatest thickness of from 600 clines and the original relation of high and low field to another. The datum from which their that near the surface the lime has been largely to 700 feet occurs in the Cumberland plateau a land has been reversed. position is measured up or down in the section is removed by percolating surface waters, leaving few miles west of Sequatchie valley, though there folds and faults. The Sequatchie valley anti­ the top of the conglomerate. It is not always behind the insoluble iron oxide as the soft ore. may be as great a thickness in the eastern part of cline is the westernmost of those remarkable par­ possible to determine this point exactly, so that The presence of lime in the ore is not objection­ Walden ridge near the center of the sheet. allel folds which characterize the Appalachian some uncertainty is thus introduced into the cor­ able, except as it renders mining more difficult, for it removes the necessity of adding limestone as a position at Kitner gap but they have never been the latter is pure, but often very thick where it Kome sandstone east of White Oak mountain flux in the furnace. The soft ore is very easy to worked. contains much insoluble matter. yields sandy soil, while the surface is rocky and mine, and considerable quantities are frequently Limestone. The supply of limestone on the When derived in this way from the disintegra­ ridgy so as to be scarcely tillable. obtained by trenching along the outcrop of the Chattanooga sheet, suitable for blast-furnace flux tion of the underlying rock, soils are called sed­ Since the sandstones of this region occupy the bed even when it is not of sufficient thickness to and for lime, is abundant and convenient of access. entary. If the rock is a sandstone or sandy shale highest land, the overplaced soils, or those washed make deep mining now profitable. This is the The Bangor limestone is most largely used on ac­ the soil is sandy, and if it is a clay shale or lime­ down to lower levels, are mostly sandy. They are character of all the ore workings on this sheet at count of its freedom from impurities and its close stone the soil is clay. As there are abrupt changes especially abundant at the foot of the escarpment present. proximity to the furnaces or to lines of transporta-' in the character of the rocks, sandstones and shales surrounding the plateaus, where the Bangor lime­ The outcrop of the Kockwood formation occu­ tion. It generally contains an appreciable amount alternating with limestones, so there are abrupt stone and its clay soil are often wholly concealed. pies a narrow strip along the eastern side of the of magnesium carbonate, which sometimes reaches transitions in the character of the soil, and soils The delta deposits formed by streams emerging Sequatchie valley, the strata dipping at low angles, as much as 35 per cent. The magnesium limestone differing widely in composition and agricultural from gorges cut in the plateaus also give consider­ 8° to 15°, toward the east under "Walden ridge. of the Knox dolomite is also somewhat used as a qualities often occur side by side. As the atti­ able areas of sandy soil overlying rocks which The corresponding outcrop of the formation on the flux, especially in the basic steel process, and is tude of the strata determines the breadth of out­ would themselves produce clay or cherty soils. west side of the Sequatchie valley is concealed by burned for lime very extensively at Graysville, crop of each formation in different places, it also Clay soils. The most productive of these are a fault, as already explained. Although the ore just off the southern edge of the sheet. determines the area of the particular soil derived derived from the Bangor and Chickamauga lime­ is not worked along this strip within the limits of Building stone. Stone adapted to architectural from each. Where the strata are nearly horizontal stones, and their distribution coincides with the this sheet, it is probably present throughout its uses occurs in nearly every formation on the sheet. at the surface, as the Chickamauga limestone at outcrops of those formations as shown on the geo­ whole extent in workable quantity. The extensive That which has been most largely used is in the Chattanooga, the corresponding soil covers a broad logic map. They sometimes have a deep red color, Inman mines are just off the western edge of the lower part of the Chickamauga limestone. At area, but where they outcrop in a nearly vertical but where the mantle of residual material covering sheet on the same belt. The ore bed is separated Hickson, on the Cincinnati Southern railroad, and position, as the same formation at Dayton, its re­ the rock is thin it is often dark bluish gray. This from the overlying Chattanooga black shale by near Chickamauga, on the Western and Atlantic sulting soil occupies only a narrow strip. is its character west of Missionary ridge and of about 60 feet of bluish calcareous shale. It has a railroad, are quarries of blue or dove-colored earthy Knowing the character of the soils derived from White Oak mountain where the largest areas of thickness of 5 J feet at Inman. limestone. The stone is evenly bedded, quite easily the various geological formations, their distribu­ the limestone occur. The rocks generally weather On the east side of Walden ridge is a strip of worked, and makes a fine building material. Sand­ tion may be approximately determined from the more rapidly where they have a steep dip than Kockwood continuous from the north edge about stones especially well adapted for foundations oc­ map showing the areal geology, which thus serves where they are nearly horizontal. Hence the soil halfway across the sheet, below which is a break cur in the Kockwood formation of White Oak also as a soil map. The only considerable areas in is deeper and more highly colored on the narrow of a few miles caused by faulting. Beyond this mountain and in the Lookout and Walden sand­ which the boundaries between different varieties belt of limestone east of White Oak mountain break the belt continues to the edge of the sheet. stones. These have as yet been quarried only for of soil do not coincide with the formation bound­ than on the broader belts of the same rocks above This southern portion is formed by two narrow local use and in a small way. aries are in the river bottoms and upon the steep mentioned. The clay soils derived from the Cam­ parallel bands which are the outcrops of the for­ Hood material. The hard blue Bangor and slopes where soils derived from rocks higher up the brian shales are somewhat less productive. The mation on opposite sides of a narrow anticline. Chickamauga limestones furnish an abundant sup­ slope have washed down and covered or mingled Apison, Connasauga and Kome shales make stiff The ore in this belt east of Walden ridge has been ply of macadam material requiring but little trans­ with the soil derived from those below. The latter bluish gray soils which are usually thinner than extensively mined both north and south of the portation. The residual chert or flint of the Fort are called overplaced soils, and a special map would those covering the limestones, the shaly structure Chattanooga sheet, but within its limits only an Payne and Knox dolomite formations is an ideal be required to show their distribution. often appearing a few inches below the surface. inconsiderable amount of surface mining has been road material and has been used very largely in Classification. The soils of this region may con­ All of these clay soils are well fitted to retain done. surfacing the macadam roads in the vicinity of veniently be classed as (1) Sandy soils; derived fertilizers, and hence with proper treatment may In White Oak mountain the greater part of the Chattanooga. from the Walden and Lookout sandstones, some be brought to a high state of productiveness. Kockwood formation consists of hard, brown sand­ Clays. The residual deposits resulting from parts of the Floyd shale, the Kockwood formation Cherty soils. More than half of the area east stones, and only the upper portion contains the the solution of the Chickamauga limestone are red of White Oak mountain and the Kome sandstone. of Walden ridge is underlain by the Knox dolo­ calcareous shales which invariably arcompany the or blue clays, and are generally well adapted for (2) Clay soils; derived from the Bangor and Chick­ mite. The soil derived from this formation con­ iron ore. On the same belt some miles toward the making brick. Some portions of the Bangor lime­ amauga limestones, the Kockwood west of the Ten­ sists of clay in which chert is imbedded. The pro­ northeast the ore forms a heavy bed and is ex­ stone leave a residual clay suitable for brickmak- nessee river, the upper part of the Floyd and the portion of chert to clay is variable; in some places tensively mined, but it decreases rapidly toward ing, and also for drain tile. Several beds of fire Connasauga and Apison shales. (3) Cherty soils; only occasional fragments occur, while in others the south, and probably does not occur in White clay which are associated with the coal probably derived from the Fort Payne chert and the Knox the residual material is made up almost wholly of Oak mountain in workable quantities beyond the contain material well adapted for making fire brick, dolomite. (4) Alluvial soils; deposited by the chert. Where the clay predominates the soil is southern edge of the Chattanooga sheet. Consid­ but they are as yet wholly undeveloped. larger streams upon their flood plains. deep red, but becomes lighter with the increase in erable ore has been taken from the surface work­ Sandy soils. Cumberland and Walden plateaus amount of chert, and in extreme cases is light gray ings on both sides of the East Tennessee railroad. SOILS. are formed by sandstones and sandy shales, and or white. Even when the proportion of chert is Lvmonite. The limonite ore does not occur in Derivation and disl/ribution. Throughout the their soil is a sandy loam. At the surface it is very large this is a strong productive soil, especial­ this region as a regularly stratified bed, but in region covered by the Chattanooga atlas sheet gray, while the subsoil is generally light yellow, ly adapted to fruit-raising. The soil derived from irregular surface deposits. Hence the limits within there is a very close relation between the charac­ but varies to deep red. In some places it consists Fort Payne chert is similar to that from the Knox which it may occur can not be indicated with the ter of the soils and that of the underlying geolog­ largely of sand, but more often contains sufficient dolomite, but the areas of the Fort Payne are much same certainty as in the case of red ore. Although ical formations. Except in limited areas along clay to give the subsoil considerable coherence, smaller and usually on steep slopes, so that its soil iron oxide is very widely distributed throughout the larger streams and on the steepest slopes, the so that a cut bank will remain vertical for some is relatively unimportant. the rocks and soil, it is only when it becomes seg­ soils are derived directly from the decay and dis­ years. The depth of soil on the plateau varies All/wial soils. Excepting the gorges of the Ten­ regated in large quantities and in a comparatively integration of the rocks on which they lie. All from a few inches to a dozen or more feet, depend­ nessee through Walden ridge, the streams of this pure condition that it is commercially valuable as sedimentary rocks such as occur in this region are ing chiefly on proximity to streams and the con­ region flow in broad valleys but they are rapidly an ore. The agency by which the segregation is changed by surface waters more or less rapidly, sequent activity of erosion. A large part of the cutting narrow channels below the general level effected is the percolating surface water, which con­ depending on the character of the cement which plateau retains its original forest growth, chiefly of these valleys, so that these flood plains, the al­ tains small quantities of weak acids derived from holds their particles together. Siliceous cement of oak, chestnut and hickory, while pines clothe luvium covered bottom lands, are- nowhere ex­ the atmosphere and decaying vegetation. These is nearly insoluble and rocks in which it is present, the steep sides of the stream channels. The prac­ tensive. The largest flood plains are along the acids dissolve the iron disseminated through the such as quartzite and some sandstones, are ex­ tice of burning off the leaves each fall prevents Tennessee river northward from the entrance to rocks. When the solution is exposed to air either tremely durable and produce but a scanty soil. the accumulation of vegetable mold and has de­ its gorge. A strip of bottom land from a quarter at the surface or in cavities under ground the iron Calcareous cement, on the other hand, is readily layed a just appreciation of the agricultural possi­ of a mile to half a mile wide usually occurs along becomes insoluble and is precipitated as the slimy dissolved by water containing carbonic acid, and bilities of this region. The Rockwood formation one side of the river with a bluff upon the oppo­ yellowish substance generally seen about mineral the particles which it held together in the rock of White Oak mountain is made up of sandstones site side. The soil of these bottoms is a rich sandy springs. This substance gradually hardens and, crumble down and form a deep soil. If the cal­ and sandy shales, and its outcrops have sandy soils. loam, containing a considerable proportion of fine where it collects in sufficient quantity, forms a bed careous cement makes up but a small part of the This is less important than that of the plateaus, mica scales derived from the crystalline rocks far of limonite or brown iron ore. rock it is often leached out far below the sur­ since the strata are steeply inclined so that they to the east. Some areas of alluvial soil also flank The only considerable deposits of brown ore face, and the rock retains its form but becomes produce ridges, and some beds of hard sandstone the smaller streams, especially South Chickamauga known to occur within the limits of the sheet are soft and porous; but if, as in limestone, the cal­ break up into blocks which cover most of the sur­ creek and Sequatchie river, constituting the most along the eastern side of the Sequatchie valley. careous material forms the greater part of the rock, face. Some calcareous sandstones near the top of continuously productive land of this region. the formation produce the small areas of deep The conditions were favorable for its accumulation the insoluble portions collect on the surface as a C. WILLARD HAYES, near the contact of the Fort Payne chert and the mantle of soil varying in thickness with the char­ fertile soil which are found at intervals along the Bangor limestone. Heavy deposits occur in this acter of the limestone, generally quite thin where summit of White Oak mountain. The strip of Geologist.