DESCRIPTION OF THE ATOKA QUADRANGLE.

By Joseph A. Taff.

GEOGRAPHY. The Red River Plain is a low, nearly flat, south- tions of the land. Under these conditions the toward the coast, but it is inclined toward the eastwardly inclined plain which extends along the channels tend to become filled and the streams Gulf at a lower angle. The Atoka quadrangle is bounded by meridians entire southern side of Indian Territory: The Red meander from side to side, broadening their The northern border of this gravel-covered 96° and 96° 30' and parallels 34° and 34° 30', It is the northern side, of the broad wverPiam. valleys. When these conditions continue unin­ peneplain is elevated approximately 600 feet and occupies one-fourth of a square valley of Red River, which slopes gently south­ terruptedly the valleys become wide and silted above the sea. Leading from it upward along and T Location of degree ot the earth s suriace. It is 34.9 the quadran- eastward toward the Gulf coast. It borders the and the hills are generally reduced to the level near the present valleys of the principal rivers, miles long and 29 miles wide, and con­ south side of the Ouachita and Arbuckle moun­ of the valleys. there are remnants of flat, meandering river val­ tains about 986 square miles. The boundary line tains and touches the Arkansas Valley province leys which are but slightly depressed below the between the Choctaw and Chickasaw nations runs between them. It joins the Prairie Plains farther GENERAL FEATURES OF THE QUADRANGLE. general level of the nearly flat rolling plain or north and south through the quadrangle about 3 west, between the Arbuckle and Wichita moun­ In the Atoka quadrangle, especially* north of peneplain and contain deposits of gravel and sand. miles from its western border. The Choctaw tains, in western Indian Territory and southeast­ the Cretaceous sediments, there are certain broad Likewise, along and near the Arkansas and Cana­ Nation lies to the east of this line and the Chick­ ern Oklahoma. At the northern border of this and well-defined topographic characteristics which dian river valleys there are remnants of wide, flat asaw Nation to the west. plain south of the Arbuckle Mountains it is are significant in considering the physiographic meandering river channels partially filled with Four topographic provinces are represented nearly 1000 feet above sea level, while south of history of the region. The first of these is limited gravel, sand, and silt. One instance has been in this quadrangle. They are the Ouachita the Ouachita Range in southeastern Indian Terri­ to a belt 10 to 30 miles in width parallel with noted where the old elevated flat Canadian channel Mountains, the Arkansas Valley, the tory it is a little over 500 feet above sea. and immediately north of the Cretaceous border. made a detour of more than 50 miles from the Arbuckle Mountains, and the Red The Arbuckle Mountain province extends from The characteristics of this topography have been location of the present river. This peneplain River Plain. With two other prov­ the vicinity of Boggy Depot, in the central part studied across the Atoka and Tishomingo quad­ stretches westward and northward across Indian inces these four constitute the physiographic dis­ of the quadrangle, northwestward rangles and the western part of the Arbuckle Territory in the eroded surface of both Creta­ tricts of Indian Territory. The others are the nearly across Chickasaw Nation. It TheMountain Arbuckle Mountains, a distance of about 60 miles. As ceous and older strata. As explained above, this Ozark Highland, which lies in southern Missouri, is about 70 miles long, and has an explained more fully under "Geology," the low­ peneplain is inclined toward the south , i.i ,1 ^ , Intersection northwestern Arkansas, and northeastern Indian average width of about 20 miles. It rises gradu­ est Cretaceous formation, the Trinity sand, was at a lower angleo than is the Cretaceous ofmarine cretaceous ero- Territory; and the Prairie Plains, which extend ally from about 750 feet above the sea at its east­ deposited upon a smooth and nearly flat floor or marine erosion plain, and near the iSdfStary from the Arkansas Valley region and Ozark High­ ern end to 1350 feet at its western end. At the plain of truncated Paleozoic rocks. This sand is northern border of the Atoka quad- Peneplainv land northward and westward across northwest­ eastern end and along its southeastern side, to the the shore deposit of the Cretaceous sea, which rangle they intersect at elevations approximating ern Indian Territory, Kansas, and Oklahoma. east of Tishomingo, it coalesces with the border­ transgressed northward and westward to an 850 feet above the sea. Toward the north the The Ouachita Mountains, whose ridges enter ing Red River Plain. In its northern and west­ unknown distance beyond the present occurrence Cretaceous plain projects above the land, while the northeastern part of the Atoka quadrangle, ern parts it rises abruptly 100 to 200 feet above of Cretaceous rocks. The land at this time was the Tertiary peneplain continues nearly level, being extend from the vicinity > of Atoka to The Ouachita_ ... the bordering plains. The high land of the probably a low coastal plain and was reduced to preserved in innumerable flat-topped ridges and central Arkansas near Little Rock Mountains. Arbuckle Mountains forms a nearly flat plain, a surface of marine planation as the sea advanced. hills of hard rocks in the Arkansas Valley region approximately 200 miles. The range is charac­ of which only the borders are deeply cut. Two Since the Trinity sand is a soft rock, it is removed and in the uplands of the broad valleys in the terized by numerous long, low mountains and small districts in the western part of this region, so rapidlyJT «/ in comparisonJ. with the wear. Cretaceous_ . Ouachita Mountain Range. The crests of many ridges, bearing generally east and west. Near known as the Eastern Wooded Hills and the West­ of the underlying hard rocks that con- £." "* of these ridges and hills are a little below the the western end, however, they trend southward ern Wooded Hills, rise above the general level of siderable areas of the Cretaceous plain erosion- general level of the peneplain, which in this and, declining rather abruptly, join the Red River the elevated mountain plain. are exposed before it is appreciably defaced. The region is about 850 feet, while a few are a little Plain. The principal mountains and groups ©f Three main river systems, the Arkansas, the exposed border of this marine erosion plain con­ higher. The higher eminences are usually table­ ridges of the Ouachita Range are separated by Canadian, and the Red, drain the whole area tinues southward along the western edge of the like, being protected by flat, hard strata, while in relatively wide, flat valleys. These valleys, where Cretaceous sediments to central Texas. ' North­ the lower hills the harder, ridge-inaking beds are of Indian Territory. * Arkansas River Main, river. they lead out from the mountains, descend gradu­ flows southeastward from the Rocky B3ta Tefri- ward the ridges of hard rock rise gradually higher either steeply upturned or are supported by thin ally to the level of the Arkansas Valley and the Mountains across the Great Plains and tory' above sea level and above the valleys until the strata only. Rising above this peneplain of level- Red River Plain on either side. Near the western the Prairie Plains, and enters the broad valley remnants of the plain can no longer be recognized. crested ridges and hills in the Arkansas Valley end of the range the crests of the ridges are at an between the Ozark and Ouachita mountains near In this quadrangle they reach an altitude of 800 region are well-defined areas where broad folds elevation of nearly 1000 feet above the sea, and the eastern border of Indian Territory. Canadian to 900 feet above sea. In the central part of the in the rocks have favored the preservation of about 400 feet above the general level of the River has its source in New Mexico, flows east­ Arbuckle region, in the adjoining Tishomingo monadnock-like mountains and peaks. Those larger valleys. They rise gradually eastward and ward across the Great Plains and Prairie Plains, quadrangle, the exposed Cretaceous marine ero­ in Indian Territory are the Sansbois, Cavanal, near the Arkansas-Indian Territory line attain and joins Arkansas River at the border of the sion plain, because of the broad expanse of hard Poteau, and Sugarloaf mountains, which rise to altitudes of about 2900 feet above the sea and Arkansas Valley region. Red River rises in New rock beneath it, extends farther north. It should heights of 1700 to 2500 feet above the sea, nearly 2000 feet above the valleys of the princi­ Mexico, flows eastward through the southern part be borne in mind that the crests of ridges and approaching the general levels of the mountains pal rivers. Eastward, in Arkansas, the elevation of the Great Plains and across the " Panhandle " high lands north of the well-defined limit of this in the Ouachita and Ozark regions. These moun­ of the ridges becomes generally less, until it of Texas, and then forms the southern boundary of plain mark only approximately the surface of the tains occupy broad synclinal folds culminating reaches 500 or 700 feet above sea level at the part of Oklahoma and all of Indian Territory. plain, for, as soon as it is uncovered the rocks in sharp crests or peaks, and are isolated in the eastern end. Likewise from the sides toward The northern tributaries of Red River in Indian begin to wear down, and only the hardest of them peneplain. The broad distribution of the surfi- the center of the range, especially in Indian Ter­ Territory drain a large area south of Canadian remain unreduced for a long time. cial deposits in the wide, shallow, and elevated ritory, the ridges increase in elevation until they River. The watershed between the Canadian A second physiographic plain, of later age and river channels and their relations to the Tertiary are classed as mountains. Jackfork, Winding- and Red rivers, especially in the Chickasaw broader exposed surface, occurs in this region. gravels, as already explained, together with the stair, Buffalo, Rich, Blackfork, Kiamichi, and Nation, lies within a few miles of the banks of The agents of erosion which have made this plain almost universally equal degradation of both Seven Devils are prominent mountains of the the Canadian. Since Canadian River, belongs to have both uncovered and obliterated much of the hard and soft rocks to the same general level, Ouachita Range in Indian Territory. Some of the Arkansas River system, the Canadian-Red Cretaceous marine erosion plain north and west strongly support the hypothesis that the surface the prominent ridges at the extreme western end watershed is a part of the divide between the of its present limits above described. Spreading stood nearly at the level of the sea when it had of the range extend a short distance into the hydrographic basins of the Arkansas and Red across the western border of the Tertiary (Eocene reached its peneplain stage. northeastern part of the Atoka quadrangle. rivers. It also divides the waters which flow and Neocene) rocks in northeastern Texas, south­ Since Tertiary time the land has been elevated The Arkansas Valley region lies between the into Mississippi River from those which flow eastern Indian Territory, and southwestern Ar­ and probably slightly tilted toward the southeast. Ouachita Range on the south and the Ozark directly into the Gulf of Mexico. kansas and extending toward the Gulf there are During and following this elevation erosion became more active and has removed the softer Mountains and Prairie Plains on the The-,,... Arkansas extensive deposits of gravel and sand on the high north, and is characterized, especially Valley resion- TOPOGRAPHY. lands. They are spread upon a peneplain, or an strata so that now the wide, flat valleys of the in its western portion, by narrow and generally eroded plain, across the edges of lower larger streams are about 200 feet below the level ORIGIN OF THE TOPOGRAPHIC FORMS. level-crested low ridges and rolling uplands. At Tertiary, Cretaceous, and Paleozoic of the Tertiary peneplain. These valleys are so the confluence of the Canadian and Arkansas The various forms of the valleys and hills in strata. These deposits extend toward wide and flat and are so nearly at the rivers this region contracts, bears southwestward, this region have been produced by the dissolving the Gulf as far as the border of Pleistocene same level that they may be considered piacinninptehee" t-t t -i . existing and joins the Red River Plain in the central part and disintegrating action of water and frost, and coastal sediments. Although the plain upon to form rudely a still lower plain rep- gwwivai- of the Atoka quadrangle, between the Ouachita by the erosion caused by rain and running streams. which these gravels were deposited has been resenting the present stage of erosion. and Arbuckle mountains. Its low level ridges The shapes of the valleys and hills and their loca­ dissected by recent erosion, yet there are consid­ Thinner, hard, steeply tilted strata and rocks and flat valleys curve around conformably with tion depend principally upon the degree of erosion erable areas near the present Cretaceous-Tertiary intermediate between hard sandstones and soft the folds of the strata in the north-central part and upon the nature and structure of the rocks. border where it has been but recently exposed or shales, give rise to various levels between the of the Atoka quadrangle. The features of the WhereJand is uplifted and tilted the streams flow is still covered by thin mantles of gravel. In the Tertiary and this latest peneplain. Arkansas Valley region, especially in this south­ rapidly and cut deep valleys. The soft rocks are Texas Tertiary region, upon the watersheds The surface of the Atoka quadrangle, when ern part, closely resemble reduced forms of the eroded more readily than hard ones, and form between the principal rivers east of the Brazos, considered in a broad way, is generally of low Ouachita Mountains. The ridges of the valley valleys, while the hard rocks remain as hills, there are small areas which rise above the gravel- relief. The larger streams meander in wide region are generally parallel with those of the ridges, and mountains. On the other hand, when covered plain to elevations approximating 700 valleys through deposits of silt and sand which range, but, with the exception of the few isolated the general surface of any land is originally nearly feet above sea, upon which the gravels do not they have deposited during floods. Where the mountains which lie in the Arkansas Valley, they level or becomes so by erosion, streams flow occur and were probably never deposited. This rocks are tilted at a low angle, as in the southern have low relief and their crests fall nearly within sluggishly and are not able to carry away all the peneplain is analogous to the Cretaceous marine half of the quadrangle, the harder limestone beds, the same plain. sediment which is swept from the higher por­ erosion plain described above in that it descends when once uncovered, resist erosion and protect the softer shales beneath, thereby forming table­ the Arkansas Valley region. These bordering which make low ridges, hills, or swales, and nearly numerous beds of sandstone, marl, and clay, with lands and escarpments or benches and terraces. low ridges of the Ouachita region are BIack Knob level plains. Clear Boggy Creek, with its wide, thicker and harder limestone strata occurring at Where the beds are steeply tilted, as in the north­ represented in the Atoka quadrangle Ridge' swampy flood plain, occupies the central part of the top. This in turn, like the Goodland lime­ eastern part of the quadrangle, the massive sand­ by only the Black Knob Ridge. This is a ridge the area of the Atoka formation in the northwest­ stone, is succeeded by soft clays and forms broad stone and flint formations stand in rugged ridges, of peculiar flinty rock, and it represents a phase of ern part of the quadrangle. table-like uplands, bordered on the north by low while the soft shales between are worn down to this topographic type not found elsewhere near The Wapanucka limestone occurs near the bor­ escarpments or steep declivities. flat valleys. The gently rolling and nearly flat the border of the Ouachita region in Indian Ter­ der of the Arbuckle highlands, but is separated South of the Caddb upland are numerous low, wooded plain that extends east and west across ritory. The strata are nearly vertical and the from it by narrow but flat plains of the Caney knobby hills and broken escarpments which rise the middle of the quadrangle is determined by ridge is quite symmetrical, with smooth, steep shale. In the vicinity of Wapanucka and in the to elevations of 750 or 800 feet above the sea. the rock formation, which is soft throughout. slopes and with many dome-like knobs in the crest. axial part of the large fold in the northwest corner These knobs are capped by the harder ferruginous The southern half of the At oka quadrangle is The central third of the ridge between North of the quadrangle this limestone produces low, beds at the top of the Bokchito formation and by a nearly level plain. A few eminences rise to the Boggy and Muddy Boggy creeks is treeless, while level-crested ridges. Elsewhere its beds are either the succeeding hard Bennington limestone. The level of 750 feet, and little of the high land the ends are covered by forests of scrub oaks. The vertical or outcrop near important streams, and most prominent of these elevations are the Caddo between the main streams falls below 650 feet. ridge ends abruptly in the northeast corner of consequently have been worn down nearly to the Hills and Sugarloaf Mountain. Other similar Beginning a little south of the middle of the the quadrangle, where the flinty formation is level of the plain. The Caney shale is a soft rock elevations occur west of Blue River. These same quadrangle there is a general rise of the land terminated by faulting. At the south end it throughout and occupies a flat plain. hard rocks form a very tortuous and rugged, toward the south a total of about 100 feet descends gradually to the plain of soft Cretaceous ArbucMe Mountain topography. The areas of though low, escarpment in the southwestern part to the watershed between Blue River and Boggy rocks. granite and Paleozoic rocks in the northwestern of the quadrangle. They also compose the floor Creek, which passes east through Caddo, at an The more rugged sandstone hills east of Black part of the quadrangle form the extreme eastern of the broad tracts of upland in the vicinity of elevation of 700 or 750 feet above the sea. From Knob Ridge have a different topographic form ; end of the Arbuckle uplift. This uplift grows Bokchito and Bennington, near the southern this watershed the surface slopes gently south­ the rocks are massive and hard and the beds are gradually broader and increases in elevation west­ border of the quadrangle. ward to Red River. In the northeastern part of tilted toward the southeast. As a result the ward. With the exception of the Sylvan shale, The topography of the elevated country in the the quadrangle, where the larger streams have northwest slopes are steepest and are strewn with the rocks involved in this uplift are generally southwest corner of the quadrangle resembles encountered hard sandstones and chert, they have bowlders and talus from the broken ledges. The hard, and, when well uncovered, stand in relief very closely that of the Trinity sand region. The cut deep and narrow valleys. Where soft rocks crest of these hills and ridges, beginning at the above the bordering plain of softer Carboniferous Silo formation, which occupies this area, is a soft are encountered the valley floors are flat and are south, rise gradually from the Red River Plain strata. sandstone and therefore the surface is undulating coextensive with these rocks. The small tribu­ northward. It has been previously pointed out The surfaces of both the hard and the soft rocks and nearly flat. Near the northern border, how­ tary streams in the more rugged northeastern that these crests, like those of Black Knob Ridge, of the Arbuckle uplift in this quadrangle lie in a ever, the streams, which fall over the steeper part of the quadrangle descend in narrow, steep lie in a plain from which the Trinity sand has smooth plain the resurrected Creta- terraces of the Bennington limestone immediately channels. been removed. ceous marine erosion plain.1 . TIn the,i TheCreta=ceous erosion below, have cut back into the Silo sandstone, pro­ The waters of the Atoka quadrangle are col­ A peculiar feature of the drainage in this region area west ot -r»Boggy T-VDepot this old11 {k'JUJjj^Plain >n the ducing rough tracts. lected in three large streams, all of which flow in is that the large streams, North Boggy and Muddy Cretaceous plain is only partially un­ Boggy creeks, flow from their flat val­ covered, while in the region west of Wapanucka GEOLOGY. a southeasterly > direction. These are _Drainage . Muddy Boggy and Clear Boggy creeks systems- leys in the soft shales without obstruc- gapf and in the northwest corner of the quadrangle PRE-CAMBRIAN BOOKS. and Blue River. North Boggy, the largest tribu­ tionA' tox the4.1. west-L across .black-Di i rrKnob -u Knob R!dge' the Trinity sand has been long removed. Here tary of Muddy Boggy, enters the quadrangle in Ridge and among the rugged hills farther east in the streams have cut channels into the softer In the eastern part of the Arbuckle Mountain the northeast corner. Clear Boggy and Muddy narrow, sharply cut channels. In recent 'geologic rocks of the Carboniferous, leaving the hard beds uplift there is a large area of igneous rocks the Boggy creeks unite southeast of the quadrangle time the Trinity sand and probably higher Creta­ in a plain nearly 100 feet in relief. This some­ eastern end of which extends into the Atoka quad­ and flow into Red River. Blue River is also ceous rocks extended over this part of the quad­ what elevated plain of hard rock has been par­ rangle. It is bounded on the north, west, and in tributary to Red River. The valleys of these rangle and the streams flowed unobstructed on tially dissected. part on the south by Cambrian and Silurian strata. streams are so wide and shallow that in times of them toward the southeast. After the streams cut This erosion plain continues westward across the Across most of the southern portion Cretaceous flood they overflow their banks more than a mile through these soft rocks into the underlying hard Arbuckle region, with Cretaceous sediments yet sediments lap upon the igneous area and conceal in places. Muddy Boggy and North Boggy beds, their channels were established and could remaining upon its southern border, as far west it in large part by residual sands. Along the creeks, which have their sources in the Carbon­ not be changed, and are now deeply cut in these as the Washita River. The plain in this western north and south margins the contacts between the iferous sandstones and shales where springs do hard rocks. part may be recognized over broader areas, since igneous and older stratified rocks are not normal, not occur, practically cease to flow during long Arkansas Valley type. The Arkansas Valley the truncated rocks are more uniformly hard. but are marked by faults. Through about one- dry seasons. Not so with Clear Boggy Creek type of topography in the Atoka quadrangle With the exception of the Washita River gorge, half mile of contact in the Atoka quadrangle, in and Blue River, which are fed continually by occurs in the north-central part of the quadran­ near the center of the region, it is but slightly sec. 28, T. 3 S., R. 9 E., and across the west end abundant large springs that issue from the great gle, between the Ouachita Mountain and Arbuckle dissected, except very near the borders, where the of the area in the Tishomingo quadrangle, the limestone formations in the Arbuckle Mountain Mountain regions, and joins the Red River Plain streams descend rapidly and where soft rocks Cambrian strata rest normally upon the igneous region. on the south near the Cretaceous border. As in occur. rocks, the lowest formation, the Reagan sandstone, the Ouachita topography in the northeastern part The rocks, especially upon the border of the being composed of the products of disintegrated TOPOGRAPHIC TYPES. of the quadrangle, the hilltops of both hard and uplift, are steeply upturned, so that the Hunton igneous rocks. These igneous rocks, consisting of The four types of topography represented in soft rocks are in the Cretaceous base-level plain. and Sylvan formations outcrop in relatively nar­ granites and associated granular rocks, are there­ the physiographic provinces of the region, which Northward the sandstone ridges and hills become row bands. The former is a hard limestone, while fore older than the overlying Cambrian strata have been briefly outlined above, occur within the gradually higher, until near the north border of the latter is a homogeneous friable shale. The how much older, a careful survey of the whole Atoka quadrangle. In describing these topo­ the quadrangle the most prominent elevations are one forms narrow, even-crested ridges, while the Arbuckle Mountain region has failed to show. graphic types it is convenient to arrange them nearly 200 feet above the general level of the val­ other is always reduced to valleys. In the axial Tishomingo granite and associated igneous under their respective provinces: the Ouachita leys. The highest crests in these ridges and hills portion of the broad anticline in the northwest rocks. The Tishomingo granite is named after Mountains, the Arkansas Valley region, the are approximately in the Cretaceous plain. corner of the quadrangle the Hunton limestone the capital of the Chickasaw Nation, which is Arbuckle Mountains, and the Red River Plain. The rocks governing the Arkansas Valley type dips at low angles toward-the east. Here it pro­ located upon it in the adjoining Tishomingo Ouachita Mountain type. The Ouachita Moun­ of topography in the Atoka quadrangle belong to duces a broad ridge with low slopes eastward and quadrangle. The granite is accompanied by tain topography is represented by the small area the Carboniferous. They are chiefly sandstones steep terrace escarpments facing westward, toward other igneous rocks which appear to be dikes, but, of rugged, hilly country lying east of the Mis­ and shales, occurring in alternate strata, with one the valley of the Sylvan shale. as has been stated, the surface of the granite area souri, Kansas and Texas Railroad in the north­ series of limestones, and in this quadrangle they Red River Plain. The whole region of the in the Atoka quadrangle is extensively covered east corner of the quadrangle. These hills are occupy chiefly a wide basin-like fold, the north Red River Plain in the Atoka quadrangle is by the sands of the basal Cretaceous formation the extreme western ends of mountain-like ridges end of which lies about 4 miles north of the occupied by the seven Cretaceous formations and it was not possible to trace intrusions in the which gradually rise higher eastward and develop border. The shales are soft and easily eroded, which are indicated on the geologic maps. Each granite for any considerable distance. In many into Rich and Kiamichi mountains in the central forming valleys and flood plains, while of these produces characteristic minor topographic places where the dike rocks were studied, the

part of the range in Indian Territory. the sandstone beds are generally0 J hard features depending upon lithologic and structural exposures are very limited and the true relations The ridges are coextensive with the occurrence .. . valleys of of the dikes to the granite could not be satis­ and stand out as more or less promi- L theValley Arkansas type. characteristics. . of hard rocks, which are either sandstones or flinty nent ridges. These rock beds outcrop The Trinity sand occupies nearly a third of the factorily determined.

strata. Between the -Lprincipal -L ridges,o ' Ridges_.. of the concentrically around this large fold, as indicated area of the quadrangle across the medial portion. The following petrographic notes are by Mr. hills, and mountains there are flat val- Muoaucntafn in part by the topography, and as can be seen on It is practically a homogeneous friable sandstone Ernest Howe. leys, which are invariably located upon reglon- the geologic map. Since the rocks dip toward or compact sand, and, except at its extreme south­ In general the Tishomingo granite is of rather coarse tex­ and limited by the surface extent of the shales or the center of the fold, the ledges of sandstone ern border, where it underlies the succeeding ture, of pinkish or reddish color, and generally poor in the shaly formations. upon the western side present their more abrupt Goodland limestone, it produces a nearly flat, ferromagnesian silicates. Biotite is always present, but in such unimportant quantities as The crests of the higher of these ridges in this faces toward the west, while those on the eastern rolling land, gently inclined toward the south. hardly to warrant calling the rock biotite-granite, but rather quadrangle lie in a plain slightly inclined toward side have their steeper slopes toward the east. Except in small areas in the northwestern part, a biotite-bearing granite. In one instance the rock, possibly the south. Southward this plain passes beneath Near the center of this syncline, in the northern the Trinity sand is covered with a dense forest, a contact facies, was somewhat porphyritic and contained biotite and hornblende in considerable amounts, together the Cretaceous strata and forms the eroded surface part of T. 1 S., R. HE., the rocks are nearly flat chiefly of scrub oak. with a generous development of the accessory minerals. The of the older rocks upon which the Cretaceous lies. and the sandstone beds make table-like elevations, The Goodland limestone is a thin but relatively constituents of the average granite are feldspars, quartz, and It is the plain of marine gradation made by the biotite. Of the feldspars, microcline is in somewhat greater sheltering from erosion the softer shales which hard formation, dipping gently toward the south. amount .than the orthoclase, while a plagioclase and micro- early Cretaceous sea. As the Cretaceous border crop in the slopes. It is continuously exposed and forms Successionof pegmatitic intergrowths of quartz and feldspar are quite sub­ is approached going south, the hills and ridges The most prominent ridge-making sandstones flat though generally narrow table- taweseasndr ordinate. As a whole, the granite of the Atoka quadrangle would be characterized as a microcline- rich granite with bio­ become lower in elevation and the valleys shal­ occur in the upper part of the Atoka formation lands and benches, with accompany- slopes' tite always present but never prominent. The accessory lower, until they merge into one another at the and in the Hartshorne, Savanna, and Boggy for­ ing escarpments facing the Trinity sand country minerals are not in any way unusual ; zircon and apatite are border of the Cretaceous deposits. quite common; magnetite is generally present, and rutile mations. The most elevated of these ridges are below. very sparingly so. Associated with the pink granite are peg­ The ridges near the north side of the Ouachita approximately 750 feet above the sea, and there The succeeding Kiamitia formation, except a matite veins which contain the same minerals as the granites region are less prominent than those in the central are occasional knobs rising to 900 feet, few thin ledges, is friable clay, forming gentle in coarse aggregates. Microcline is the prevailing feldspar, and muscovite is not uncommon, but is never in greater quan­ part, and decrease in elevation in that direction The McAlester shale and the lower part of the prairie slopes leading up to the outcrop of the tity than biotite. Garnet occurs in some as an important until they are on a level with similar ridges in Atoka formation contain thin sandstone members Caddo limestone. The Caddo formation has accessory.

i Occurring with the granites and hardly to be distinguished (Ordoviciau) age. The Reagan sandstone was stone for probably 2000 feet above, have been thickness between 400 and 500 feet. They make from them in hand specimens are monzonites extremely rich classified accordingly as Silurian, but should referred to the upper Cambrian. The age of these a lithologic transition between the Simpson and in quartz. Of their relative importance and their general mode of occurrence practically mon^onite. be mapped as Cambrian, since numerous fossil fossils had not been determined at the time the Viola formations, though the beds are for the nothing is known. A plagioclase feldspar, remains of* mollusks and crustaceans occurring maps were printed and on them the whole forma­ most part closely related to the former. andesine, is equal to, or even greater than, the orthoclase; and microcline, when present, is subordinate to both. in the upper calcareous layers of this formation tion is classed as Silurian. The very The Simpson formation throughout contains Quartz is extremely prominent, generally more so than the in the Tishomingo quadrangle show that the rocks abundant fauna in the upper transition thick iime- an abundance of fossil shells which show that it ferromagnesian silicates, which may be hornblende or biotite are of Cambrian age. beds at the top of the formation, as belongs in the lower Silurian (Ordovician). with very little pyroxene, either diopside or augite. The well as that occurring down to a horizon probably Viola limestone. The Viola limestone receives accessories are magnetite, titanite, and apatite. In addition CAMBEO-SILtlElAlSr BOOKS. to the quartz-monzonites a specimen from one locality has 3000 feet lower, is of lower Silurian (Ordovician) its name from the village of Viola, which is located been called a diorite, although it can hardly be distinguished AfrbucTde limestone. This formation occurs in from one of the monzonites in the hand specimen. The mate­ age. More precise correlation of the Arbuckle close to the occurrence of the formation 5 miles rial from which the thin section has been made is considerably five separate areas in the Atoka quadrangle, and limestone can not at present be made. west of Wapanucka. This limestone crops out decomposed, so that the feldspars can not .be satisfactorily is nowhere in undisturbed or normal contact with in four narrow exposures near the northern determined, but the plagioclase seems to predominate, with SILUBIAN BOOKS. only a very little orthoclase. Hornblende as an original min­ the underlying formation except in sec. 28, T. 3 S., border of the granite and in a fifth and much eral equals the feldspars in amount, and a little biotite also is R. 9 E., where it is found in regular stratigraphic There are two areas of Silurian strata in the larger area in the northwest corner of the quad­ present. succession upon the small area of Reagan sand­ Of the six specimens of dike rocks examined which cut the Atoka quadrangle, one in the northwest corner rangle. Full sections of the Viola limestone are stone. No exposure of the top of the Arbuckle pink granite five are diabase, while the sixth, though much and the other in the northeast,7 belong-& T_ WO distinct.. .. , exposed only in the two localities west of Wapa­ altered, is taken to be one of the iamprophyres, _ . ... , ' , ,., ,.,, ^ ,f ,, Basic dikes, limestone is known to occur in the Atoka quad­ ing respectively to the Arbuckle Moun- |nruria°n nucka. In these and the other two areas near probably a kersantite. With one exception the diabases contain only the bare essentials, labradorite and rangle. On account of the very extensive folding tain and Ouachita Mountain uplifts. the granite the rocks dip steeply toward the north, augite, with magnetite and apatite as accessories. The excep­ and faulting which the Arbuckle limestone has Although these areas are less than 20 miles apart, while in the large area to the north, where only tion contained biotite in fair amount. The rocks are fairly suffered the dips of the beds and the true order fresh, but in most augite has been more or less altered to the formations are lithologically different and can the upper part of the formation is exposed, the hornblende. The feldspar is labradorite having the composi­ of succession could not be made out in a con­ not be correlated, except in a general way by fos­ dips are low toward the east. tion Ab3 An3, and it is extremely fresh. Kaolin, chloritej siderable part of the area. The surface of the for­ sil remains. In the Arbuckle area the formations The Viola formation represents a continuous and the hydrous oxides of iron are the common alteration products. In all, the structure is strongly ophitic, even in one mation for the most part is a smooth plain, and the are chiefly limestones, while in the Ouachita they and slightly variable deposition of limestone case where the rock was included by the granite without rocks are partially obscured by a residual mantle are almost entirely shales and siliceous sediments. approximately 700 feet thick. In fresh exposures clearly defined limits. The lamprophyritic dike is almost too of Trinity sand, which until recently covered them far gone for satisfactory determination. A feldspar, appar­ In the Arbuckle region the upper Silurian is rep­ the limestone is massive in appearance, with strati­ ently orthoclase, is almost entirely altered to muscovite. entirely, so that fragments of the limestone or an resented by limestone containing abundant fossil fication planes faintly showing. On weathered With this is biotite, hornblende, and quartz, named in the occasional ledge projecting through the sand or remains, succeeded by Devonian sediments several surfaces there are shown beds of limestone rang­ order of their importance. Hornblende is so much decom­ posed that it can not be determined satisfactorily as an soil are the only exposures found over much of hundred feet in thickness. In the Ouachita region ing in thickness from thin strata to a few feet, original mineral. The biotite is the only fresh mineral present. the surface. In the area north of Rock Creek, occur local cherty deposits which are upper Silu­ and with them are occasional irregular bands and Supposing the feldspar to be orthoclase, and the hornblende, in sees. 28, 20, and 21, T. 3 S., R. 9 E., it is esti­ together with the biotite, to be original minerals, this rock rian while Devonian strata are not known to occur. nodular masses of chert or flint. This chert is will be placed as one of the kersantites. mated that 2000 feet of the formation are exposed The lowest Carboniferous formation, a deposit of most abundant in the lower and middle portions from the base upward. Nearly as great a thick­ black shale, extends from one region to the other, of the formation. The texture of the limestone SEDIMENTARY BOOKS. ness of the limestone is exposed in the southern­ resting upon Devonian rocks in the Arbuckle for the most part is fine and dense. Some beds CAMBBIAlsr BOOKS. most area, which apparently belongs in the upper region and upon Silurian in the Ouachita region. are coarsely crystalline, while others are com­ half of the formation. The middle and largest For these reasons it is more convenient to discuss posed chiefly of shells and shell fragments. The Reagan* sandstone. This sandstone is repre­ area is not sufficiently exposed to yield a section of the Silurian formations in each province separately. abundant fauna occurring throughout the Viola sented in the Atoka quadrangle by a single out­ the rocks, since the surface is flat and largely soil . limestone show that it is of lower Silurian (Ordo­ SILURIAN ROCKS IN THE ARBUCKLE UPLIF^f. crop in sec. 28, T. 3 S., R. 9 E. The east end of covered. The limestone of the two areas lying vician) age. the outcrop abuts nearly at right angles against north of the granite is for the most part well Simpson formation. This formation is exposed At the base there is a gradual transition from the granite, from which it is separated by a very exposed, but the original structure is so obscured in the Atoka quadrangle in two small are|as near thin-bedded shell limestone and greenish shale of profound fault. Toward the west it passes uncon- by faulting, probably within the formation as the western border, west of Wapanucka. In both the Simpson formation into the mass of the Viola formably beneath the Trinity sand, the basal for­ well as upon both sides, that little could be made instances it is separated from the Arbuckle lime­ limestone, while at the top there is an abrupt mation of Cretaceous age. The Reagan sandstone out concerning the thickness of the strata or posi­ stone by faults, the lowest beds of the Simpson change from limestone to the dark-blue and green­ occurs along the swampy valley of a small tion in the formation. These limestones are dull being also concealed. The upper part of the for­ ish shales of the succeeding formation. stream, so that the lower beds of the formation blue to cream colored and generally massive. mation, on the contrary, is fully exposed! and is Sylvan sliale. This formation takes its name as well as the granite beneath are concealed by When compared with the strata of the continuous succeeded in regular order by the Viola lime­ from the village of Sylvan, in the central part soil and sediment. The exposures of these beds section of the same formation occurring in the stone. In both areas also the rocks dip jtoward of the Tishomingo quadrangle, near which it is in the Atoka quadrangle are not sufficient to middle and western part of the Tishomingo quad­ the north and are parts of the northern limbs of typically exposed. It is a formation of soft, afford a clear description of the nature of the rangle there is little doubt that they belong within anticlinal folds. In both areas also the rocks greenish, fissile shale which weathers easily to a the lower half of the formation. occur near the northern border of the highland formation. The part of the formation exposed, fine soft earth. In the Atoka quadran­ Soft, green­ however, consists of many thin beds of brown Farther west this formation composes the central made by the granite and associated rocks, and gle it is estimated to be not more than ish shale. quartzitic sandstone and grit in the lower part mass of the Arbuckle Mountains (from which it are trenched by small streams, in consequence of 50 feet thick, while farther west, in the Arbuckle and thinner calcareous sandstones with shale receives its name), where it has an which they are well exposed. Mountains, it increases to nearly 300 feet. The Thick sec­ estimated thickness of 6000 feejfc. In tion of lime­ The thickness of the> Simpson formation is layers in the upper part. Near the eastern end stone. Sylvan shale rests upon the Viola limestone and prominent ledges of brown gritty sandstone are this region it is folded into a broad estimated to be 1500 feet. In the Tishomingo is succeeded as abruptly by nearly equally hard exposed near the top of the formation. In the steep-sided arch, which is itself folded and faulted, quadrangle and in the Arbuckle Mountains beds of the Hunton limestone. middle of the area only occasional outcrops of and in many places complete sections of the for­ farther west, where the formation is completely As the Sylvan shale is a soft rock, it invariably thin beds are seen. At the western end, very mation may be observed. It is composed chiefly exposed in many places, it varies in thickness occupies swales or valleys between the harder near the southwest corner of sec. 28, occur expo­ of hard bluish-white and cream-colored limestone from 1200 to 2000 feet. limestone ledges of the contiguous formations. sures of quartzitic sandstone in thin layers, which stratified in thin layers and beds reaching 3 feet It is composed of sandstones and fossiliferous The talus from these adjoining limestones covers show a thickness of nearly 200 feet. The varia­ in thickness, interbedded with slightly argillaceous limestone with interbedded greenish clay shales a large part of the outcrop of the Sylvan; and ble dip of the rocks here, together with marked layers. Occasionally siliceous limestone and shale and marls, which may be separated into several since the shale is occupied by forest, it is rarely jointing, indicates probable displacement of the beds were noted. Still less common are thin quite distinct members. At or near the base, exposed, and at no place is it completely exposed. strata and possible exaggeration of the true thick­ layers of chert and cherty oolite and limestone near the top, and in the central portion there are The Sylvan shale crops in four separate areas, ness of the formation. breccia or intraformational conglomerate. In this members of sharp, brown, and in places massive three of which lie near the northern border of In the central part of the Tishomingo quadran­ region, where the beds are more or less steeply sandstone. Many of the beds occurring in these the granite. A fourth and the largest area occurs gle, which adjoins this quadrangle on the west, tilted and generally exposed, they occur at the members are composed of nearly pure gritty near the northwest corner of the quadrangle. In there are complete exposures of the Reagan for­ surface in miniature ridges a few feet in height, quartz sand. In places such sandstone beds are the three southern areas the formation dips steeply mation in the vicinity of Reagan, from which vil­ depending upon structure and composition. The several feet in thickness, occur without distinct to the ^northeast, while in the northern it dips at lage the formation derives its name. Here it rests harder and more crystalline the limestone the bedding, and are indurated, while at other local­ a low angle toward the east and north. upon the uneven eroded surface of the granite, greater the resistance it offers against the agents ities they are found in compact but unconsolidated The Sylvan shale represents an interval of time and varies from thin calcareous sandstone strata of disintegration. beds. Occasionally there are various beds, some between the known lower Silurian, or Ordovician, to a formation nearly 300 feet in thickness. In At the base there are thin sandy limestones of which are limestones interstratified with the and the upper Silurian in this region. Fossils contact with the granite in places there which form transition strata, 200 to 300 feet thick, sandstones. These sandstone members range in have been found only in the green shales near the are beds of arkose consisting of granitic ?n thearkose from the Reagan up to the purer limestone of the thickness from thin strata to beds aggregating base of the formation, in two localities near the materials more or less completely dis­ Arbuckle. Succeeding these are 500 to 600 feet 100 feet, the lower and middle sandstones usually north-central part of the Arbuckle Mountains, and integrated. These arkose beds are usually suc­ of dull-blue or cream-colored limestone. Much of being thicker than the upper one. The outcrops indicate lower rather than upper Silurian age. ceeded by quartzose grits consisting of sorted crys­ this massive limestone weathers into very irregular of the sandstone are marked by timber, while the Hunton limestone. At the close of the Sylvan talline quartz grains, while higher still are finer brown and sometimes black bowlders. These intervening strata are generally occupied by shale epoch there came a change in sedimentation and less pure sandstones wTith shale layers, fol­ strata are succeeded by white limestone beds of prairie. and nearly pure white limestone and limy marls lowed by calcareous sandstones, which are overlain variable hardness, which continue upward to The limestone and marl members of the Simp- were deposited to a thicknessr of approximately by the limestone of the succeeding formation. within 400 or 500 feet of the top. As the top of son formation, except the transition beds at the 150 feet. This limestone takes its nanaa from Fossils from the Reagan sandstone were not the formation is approached the beds become top and bottom, lie between the upper and lower the village of Hunton, near which it is typically observed in the Atoka quadrangle, nor elsewhere thinner and less pure, finally culminating in sandy sandstone members and are separated from each and completely exposed. Here also it contains in the Arbuckle Mountain region, until after the and marly limestone which contains occasional other by the intermediate sandstone. They are in great numbers well-preserved fossils of upper classification of the rocks had been made and the beds of clay and thin sandstone strata. These composed usually of thin yellowish or bluish Silurian type. The formation represents the maps for the folio printed. The lowest fossils beds mark the transition from the pure limestone limestones with greenish marly clays interstra­ closing episode of Silurian time in this .region. that had been obtained at that time were those of the Arbuckle to the lowest sandstone member tified. In places some of the limestone beds are The Hunton limestonev varies in thickness in in the succeeding formations of lower Silurian of the succeeding Simpson formation. .white and pure, and at all localities a large part the Arbuckle uplift from a thin bed to about 300 Fossil shells, which occur abundantly in the is composed of fragments of fossil shells. Above feet. Near the Ouachita River, in the southern * On the maps this formation name is spelled Regan; but as lower transition beds at the base of the Arbuckle it is derived from the name of the town of Reagan, the spell­ the uppermost sandstone member there are inter- portion of the uplift, it is absent for a space of 10 ing here used is correct. limestone and less abundantly in the purer lime- stratified shell limestones and clays ranging in miles. In the northern and eastern parts of the Atoka. uplift the formation is practically the same as that under the heading "Geologic Structure," it is which a large part of the formation is exposed. was found embedded in this stratified chert. shown in exposures near Hunton. Beginning at steeply tilted toward the east. At the southern end It is estimated that about 3800 feet of this for­ Fossil shells are of rare occurrence in the Wood- the base, there are variable beds of it comes from beneath the flat Cretaceous rocks, mation from the base up are exposed in the Atoka ford formation, but those found in the chert west white oolite, in parts of which coarse Bedsstratified of and at the northern end it is cut off abruptly by quadrangle. It crops in one large and three small of the Atoka quadrangle proved to be of Devonian ' -L oolite.«ni;+a and fine spherical granules appear as an extensive fault, along which the rocks have areas in the hill country in the northeastern por­ age, while others found near at hand in the clay if originally sorted and stratified. Elsewhere been thrust upward and westward. tion of the quadrangle. These areas are the shale immediately above the chert are of lower spherules ranging in size from that of a small The formation takes its name from the town of extreme west ends of large exposures which Carboniferous age. pea to fine grains appear intermingled. In places Talihina, in the Tuskahoma quadrangle, near extend into the Ouachita Range, making the CAKBOKIFEKOIJS ROCKS. also the oolite is silicified, so that bowlders and which place it occurs with large exposures in the Rich, Jackfork, and Kiamitia mountains. fragments of the siliceous oolite are left upon the mountains. The Jackfork sandstone consists of a series of Caney shale. Shales of lower Carboniferous surface after the limestone has been removed. The Talihina chert is approximately 1200 feet generally even-textured, fine-grained, brown and age, known as the Caney shale, succeed the Following the oolite are bluish and cream-colored thick and is composed of three not very well- gray sandstone strata ranging from thin layers to Woodford chert in the northwestern part of the Atoka quadrangle and elsewhere throughout granular and fine-textured limestones and marly defined members. The lowest of these Chert,.,._.. beds massive beds 50 feet in thickness. Occasionally beds attaining a combined thickness of about 100 members consists of flint, chert, black interstratified with these beds are thin strata of the Arbuckle Mountain region. The same forma­ feet. Many of the beds in this part of the sec­ and bluish shales, and lentils of dense Ridge> clay shale and shaly sandstone. The shaly beds tion in the northeastern part of the quadrangle is tion are crystalline and hard, while others are limestone interstratified. It is estimated to be are very rarely exposed on account of the protec­ concealed by displacement along the fault which composed in large part of comminuted shell frag­ 600 feet in thickness. In most parts these flints, tion afforded by the sandstone beds and sandstone separates the Silurian from the Carboniferous ments. Near the top are marly beds which carry cherts, and limestones are in sheets rarely exceed­ talus. rocks. This formation outcrops, however, in an abundance of well-preserved fossils, some of ing 6 inches in thickness, while the shales occur The Jackfork formation has not yielded fossils numerous places farther east in the Ouachita which are silicified. The uppermost 50 feet of as thin laminae or fissile layers. The cherts and of any kind, but in the Kiamichi Mountains, on Range and is found resting upon the Silurian the formation is for the most part hard and thin flints are black, gray, whitish, with a few green­ the southern border of the McAlester quadrangle, limestones and cherts which occur above the great bedded. Many nodular cherty concretions and ish flinty beds in the upper part. This member it is directly overlain by thin limestone and cherty thickness of sandstones and shales in the north­ numerous fossils, some of which are beautifully grades up into the middle member, which is com­ strata of lower Silurian age (upper Ordovician). eastern portion of the quadrangle. silicified, occur in these beds. posed of fissile shales and thin cherty layers and Occurring, therefore, between two formations con­ The Caney shale in its lower part consists of has an estimated thickness of 300 feet. It occurs taining upper Ordovician fossils, the Jackfork black, bituminous, fissile shale with spherical SILURIAN ROCKS IN THE OUACHITA UPLIFT. at the eastern base of the prominent ridges made sandstone is also of the same age. calcareous segregationsDO and irregular,o "> Black_, , bitu-_ In the western part of the Ouachita Range by the lower chert, and in consequence is almost In Caney Creek Valley, at the southern border dense, blue limestone bodies. This min°«sshale- there has been uplifted a mass of Silurian (more invariably concealed beneath the abundant talus of the McAlester quadrangle, these Silurian lime­ bituminous shale is succeeded by clay shales specifically, upper Ordovician) strata aggregating from this chert. This member also grades upward stones are succeeded by the Caney shale of the which include small ironstone concretions and approximately 12,000 feet in thickness. It is into the upper chert in such manner that its limit lower Carboniferous, which formation occurs with occasional calcareous septaria. estimated that more than 11,000 feet of this sec­ can not be well defined. The upper member is but little variation in both the Ouachita and the The surface of the Caney shale area is flat, and tion are exposed in the northeastern part of the also estimated to be about 300 feet in thickness, Arbuckle Mountain sections. At other localities the rocks are so concealed that the structure can Atoka quadrangle and are included in four dis­ and is composed of chert and shale in all respects in sees. 3, 4, and 5, T. 2 N., R. 15 E., in the same not be made out with sufficient accurracy to deter­ tinct formations described below. like the lower member except that the individual quadrangle, upper Silurian chert and limestone mine the thickness of the formation. It is roughly Fossil remains have not been found in the layers are generally thinner. Exposures of this strata immediately underlie the Caney formation. estimated, however, to be 1600 feet. Stringtown shale, the lowest formation, except member have not been found sufficiently fresh to The formation outcrops in a very irregular DEVONIAN HOCKS. area across the eastern end of the Arbuckle uplift at its top.-L These fossils,' with those Correlation_ , .. indicate the presence of limestones. This chert occurring in the Talihina chert, in the IJiJ AlSSSie produces a line of low, round knobs and occasion­ Rocks of Devonian age, so far as at present and is limited upon the eastern side by the out­ upper part of the Standley shale, and sediments- ally ridges which lie at the eastern bases of the determined, are confined to the Woodford chert, crop of the succeeding Wapanucka limestone. It in the limestone immediately above the Jackfork prominent ridges and knobs made by the lowest which rests conformably upon the Hunton lime­ is cut by numerous normal faults, shown upon sandstone, show that the whole series of rocks member of the formation. stone, which is of Silurian age. This formation the map, which bring it in contact with all the belongs to the upper Ordovician division of the On account of the variable strata and thin beds, is known only in the Arbuckle uplift, around and formations below it in the region except the Silurian and is of the same age as the Viola lime­ the talus of angular and sharp chert is thick from in which it is found where there are suitable con­ Reagan sandstone. Such faults, which bring stone, which occurs in the upper part of the the bases of the hills almost to the crests, except ditions for its exposure. formations of different nature in contact, can be Silurian section in the Arbuckle uplift. where the rocks are being actively eroded by the Cherty beds occur in the Ouachita uplift east easily detected, whereas faults within the shale Sfringtown shale. Only the upper part of this streams. of the Atoka quadrangle directly beneath the for­ can not be located. Local narrowing of the Caney formation comes to the surface in this quadrangle, Standley shale This formation follows the mation which overlies the Woodford chert in the shale outcrop, such as that 1J miles west of Wap­ and the base of the formation has not been Talihina chert in gradual transition. Siliceous Arbuckles, but fossils from these cherts belong anucka, can only be explained by faulting within observed anywhere in Indian Territory. The chert, black shale, and greenish clay shales to the upper Silurian. The stratum or interval the shale, but the line of displacement can not be only clear exposure of the shale in the Atoka occur in alternate members for nearly 800 feet which represents the Devonian as it is known in determined. quadrangle is in one small area about a mile above the base. There are two cherty members, the Arbuckle uplift is concealed by faulting at The black shale in the lower part of the Caney southeast of Atoka. It occurs below the Talihina 30 and 40 feet in thickness, which were noted in the western end of the Ouachita uplift in the formation contains fossil remains of lower Carbon­ chert which forms Black Knob Ridge, and crops sec. 7, T. 2 S., R. 12 E., 550 and 800 feet, respec­ northeastern part of the Atoka quadrangle. These iferous (Mississippian) age. The blue shales along the western side of it, between Stringtown tively, above the base of the formation. These Devonian rocks have yielded but few fossils, and higher up in the formation have not yielded and the Cretaceous area to the south. It is cherty strata resemble many of the thin and more the exact parting between the Devonian and Car­ fossils, and the dividing line between lower and limited on the western side by Carboniferous shaly cherts found in the Talihina formation. boniferous can not at present be determined. The upper Carboniferous is not known, since the lime­ strata, from which it is separated by the great Continuing upward in the section, there are fossils obtained from the Woodford chert, how­ stone immediately succeeding is of Coal Measures fault which follows the western border of the greenish and dark shales alternating with drab ever, show that the larger part of the formation (upper Carboniferous) age. Ouachita uplift in this region. This faulting is or brown and moderately hard sandstones until belongs to the Devonian. Wapanucka limestone. The Wapanucka lime­ described under " Geologic Structure." the formation reaches an estimated thickness of Woodford chert. This formation outcrops in stone has been traced throughout the extent of its The single locality southeast of Atoka where 6000 feet. Distinct sandstone members range in the Atoka quadrangle in five separate areas. In outcrop from the northeastern side of the Arbuckle this formation is partially exposed shows the thickness from 20 to 100 feet and are Thlcksection the three areas lying north of the granite it is uplift northeastward along the north side of the shales to be very much crushed and deformed, so separated by shales or shales interstrati- of shales- steeply upturned, dipping toward the northeast, Ouachita Range nearly to the Arkansas State line. that no reasonable estimate of the thickness could fied with sandy beds 140 to 2000 feet in thick­ while in the large area in the northwest corner of Broadly considered it is a lens 400 feet thick in be made. What appeared to be the upper part ness. The best section of the formation in this the quadrangle it dips low toward the east across the middle, thinning out at its edges. Across the of the formation is a black, fissile, cherty shale, quadrangle was noted across sees. 7, 8, and 9, T. the axial part of the large fold. At the southern Atoka, McAlester, Tuskahoma, and part of the and below it are green clay shales. Elsewhere 2 S., R. 12 E. border of the large Silurian area 2 miles north­ Coalgate quadrangles, however, it is continuous; in the quadrangle the formation makes smooth The sandstones are so soft that they produce west of the Chickasaw Rock Academy another although it varies somewhat in thickness, it is to slopes, in most part prairie land, and there is no little more effect upon the surface configuration small outcrop was observed. be considered a formation. indication of other rocks than shales beneath the than do the clay shales in which they are embed­ The Woodford chert is composed of thin strata This limestone occurs only in the northwestern soil. ded. The whole formation invariably crops in of dark chert, cherty shale, and black, fissile, bitu­ part of the quadrangle. The displacement along The upper part of the Stringtown shale crops "nearly level plains or valleys and in such steep minous shale aggregating 500 to TOO feet in thick­ the great fault west of Black Knob out in the dome-like uplift 8 miles northeast of slopes at the borders of these valleys as are pro­ ness. The formation is variable as to thickness Ridge in the northeastern part of the iferous1 nmel Tuskahoma, near the center of the portion of the tected by the harder overlying formation. and as to position of the beds which compose it. quadrangle has caused the Silurian Ouachita uplift in Indian Territory. It occurs The Standley shale is found in the wide valley In places the cherty beds approach fiint in tex­ strata to be brought in contact with Carboniferous in this locality in a fiat circular cove surrounded plain extending from the northeast corner of the ture,' and some layersJ are several inches Beds_ ^ of flinty rocks younger than the Wapanucka limestone, by prominent ridges of the overlying Talihina quadrangle down Chickasaw Creek and across in thickness. Locally such beds make chert- thereby concealing it from view. Two normal chert. The upper part of the shale crops beneath North Boggy and Muddy Boggy valleys to the a large part of the formation, occurring in either faults, one upon each side of the flat-pitching anti­ the talus of this chert, while the soft green shales broad plain of the Trinity sand south of Atoka. the middle or lower portion. Elsewhere little can cline in the northwestern part of the quadrangle, lower in the formation lie in the flat, partly It also extends eastward up Chickasaw and Little be found except thin, fissile, siliceous black shale. displace the Wapanucka limestone for a distance wooded plain of the cove. The upper part is Chickasaw creeks, joining. the broader plains Locally also bluish shale has been noted. inter­ of about half a mile. Elsewhere the formation composed of black, siliceous, slaty shales similar and valleys of McGee and Jackfork creeks and stratified with black shale and chert. Near the crops in its normal position. to those in the vicinity of Atoka and contains Kiamichi River in the central part of the Ouaehita base of the formation in places there are lentils The formation comes from beneath the flat lower Silurian graptolites (upper Ordovician age). Range in Indian Territory. The formation takes its and large concretions of almost pure flint. Cretaceous deposits one mile northwest of Boggy Below these beds are greenish fissile and friable name from the village of Standley, in 'the Kiamitia Some of the cherty beds are in places calcareous Depot and continues northwestward in its tortu­ shales with occasional inclusions of calcareous Valley, where it is extensively exposed. and approach siliceous limestone. Certain flint ous outcrop to about -6 miles beyond the north­ cone-in-cone and ironstone concretions. Jackfork sandstone. The Jackfork sandstone shales contain numerous small, round, marble-like west corner of the quadrangle, where it becomes Talihina chert. This formation occurs at the is the mountain-making formation of the Ouachita concretions which may be phosphatic. so thin that it can not be traced farther. At this surface in this quadrangle only in Black Knob Range in Indian Territory. It repre- Thicksection Large fragments of silicified fossil wood have western extremity it joins beds of limestone con­ Ridge, which extends from a point 2 miles south sents an almost continuous sedimenta- ofsandstones- been noted upon the surface of the Woodford glomerate which thicken westward to enormous of Atoka nearly to the northeast corner of the tion of 5000 feet of brown and gray sandstone. chert and at one locality in the adjoining Tisho- proportions around and across the northwestern quadrangle. With local exceptions, to be noted It receives its name from Jackfork Mountain, in mingo quadrangle a broken trunk of a fossil tree part of the Arbuckle Mountain uplift. The width of the outcrop of the formation is the lower beds of the Atoka formation have been strata, outcrop in low ridges west and southwest in some places exceed 600 feet. Some of these governed chiefly by variations of dip but also in so folded and faulted that the same beds are of Lehigh. Two or more thin beds of sandstone sandstone beds, a large part of which are com­ part by the limestone ridges, though there is a repeated many times in long, narrow, parallel occur also in the upper part of the formation, and posed of chert conglomerate, are like those in the slight thinning of the rocks from southeast to belts for a width of nearly a mile. Southeast of in places make low hills, but their ledges usually lower formations in the eastern portion of the northwest. Where the formation is shown in its this faulted strip the sandstone and shale beds do not outcrop. In the western part of the Lehigh basin. narrowest outcrop in the southern part of T. 1 S., are folded and steeply inclined toward the south­ Lehigh basin, where the rocks dip at low angles, The sandstones in the upper part of the forma­ E. 8 E., the dip is 60° to TO0. Elsewhere the dip east. the various beds occur in broader areas. Between tion in the Coalgate quadrangle vary but little in varies from 10° to 15°. Northwest of Wapanucka OJiickachoc chert lentil. The Chickachoc cherty the low ridges of sandstone the shale surfaces are physical character and are generally brownish or and in the axial part of the anticline in the north­ sandstone is a lentil in the lower part of the A.toka spread in wide, flat, and shallow prairie valleys. gray, and in places rather ferruginous. The west corner of T. 1 S., R. 9 E., the limestone formation and occurs in the faulted strip above In the eastern part of the basin where the forma­ shales are exposed to only a very limited extent makes considerable ridges, thereby broadening the referred to. Because of its peculiar and charac­ tion is steeply upturned, the outcrops are narrow. on account of the generally low relief of the land outcrops. teristic texture and hardness it has been separated The surface is more elevated and the harder beds and the wide, shallow valleys of the streams, but Southeast of Wapanucka the formation is from its associated beds and mapped. It is about make rough low hills and ridges. Like the Hart­ in the few steep slopes and stream cuttings where approximately 125 feet thick, and is composed of 80 feet thick and is composed of stratified, yet shorne sandstone the sandstones of this formation fresh exposures were observed they consist of several members of calcareous and cherty sand­ massive, calcareous and cherty sandstone. There occur in the western part of the Lehigh basin, laminated, bluish, clay shale, containing small stone, limestone, and shale. An exposed section is but little variation in the character and texture while in the eastern portion many of the sand­ ironstone concretions, thin, wavy, sandstone plates, in the NW. J of sec. 32, T. 2 S., R. 9 E., shows of the rocks in the Chickachoc lentil. Occasion­ stone beds are replaced by chert conglomerates. and shaly sandstone beds. Boggy Creek, which at the base 36 feet of shale and calcareous brown ally however, thin stringers of almost pure flint There are two coal beds in the McAlester shale; flows along the eastern side of the area, affords a sandstone, followed by 24 feet of shaly and hard and siliceous limestones occur in exposures of one at the base and the other about 200 feet below number of exposures of bluish shales in the lower bluish limestone. Above this limestone there are unweathered rock. When weathered the whole the top. Both of these beds are of part of the formation. 15 to 20 feet of dark-blue and black fissile shale. mass becomes nearly white and breaks down into workable thickness and the upper one Thebearing coal= tor- In the lower part of the formation as exposed The shale is succeeded by 10 to 12 feet of hard, thin, coarse, hackly plates, which feel as if com­ is extensively mined in the vicinity of east of Lehigh the sandstone and conglomerate cherty limestone and calcareous sandstone which posed of sharp grit. The folding in this part of Phillips and at Lehigh. The coals in this forma­ beds are thickest and make rough ridges and in turn is followed by beds of hard limestone 40 the Atoka formation has been so exces- Sharp_. parallel tion will be considered under the heading " Coal." hills. Certain shale beds which lie nearly flat in feet thick. Succeeding strata to the top of the sive that the beds are now mostly .?y !etaSitcde

Another member near the base makes local rough where locally worn down by Boggy Creek, they and southwestern portions of the same basin or foreignO to the region,o ' while the chert Local, , chert. , sandstone hills southeast of Wapanucka. Promi­ form narrow, sharp ridges. Going eastward around syncline the sandstone ridges are generally covered is local, being derived from the Talihina ?n tSScreE8 nent local beds of conglomerate composed of fine the southern side of the Lehigh basin the beds by strips of forest while the valleys are prairie or chert, near which it is most abundant ceous> brown sand and subangular chert pebbles make change from a brown sandstone to a chert con­ open timber land. Here the sandstone beds gen­ in the vicinity of Black Knob Ridge. Upward high ridges and hills immediately west and south­ glomerate with a matrix of brown sand. In the erally dip at low angles, the ridges are less promi­ the conglomerate pebbles become smaller, grading west of Stringtown. Conglomerate beds of similar southeastern part of the basin, opposite nent, the valleys wider, and there is less diversity finally into grits of quartz or chert. nature occur also in the upper part of the forma­ the southern end of Black Knob chert ?he?tncon!he in the landscape. The conglomerate at the base of the formation tion west of North Boggy Creek and north and ridge, a large part of this formation is No coal of any importance has thus far been is coarsest and most abundant in the region south west of Atoka. A peculiar feature of this chert chert conglomerate which continues along the located in the Savanna formation. It was reported, of Atoka. In the western part of the quadrangle, conglomerate is that its limit in range eastern side of the syncline to the northern however, that coal beds had been found where the Trinity sand overlies the granite, the ^ . -I'-ii Carboniferous north and south corresponds with the chert con=. border of the quadrangle. It is evident from in the vicinity of Nixon, 6 miles north- basal part of the formation is composed chiefly of L glomerate in strata. occurrence of Silurian chert in Black Biac^Knob this fact that during this portion of Carbon­ west of Phillips, but their thickness quartz grit derived from the disintegrated granite. Knob Ridge. The sandstone strata in Rldge' iferous time the Silurian chert beds of Black and extent were not determined. The basement rocks here are composed of hard the northwest corner of the quadrangle are in Knob Ridge or its former extension contributed Boggy shale. Above the Savanna sandstone limestone and granite, and it is striking that both many respects unlike those of the northeast corner. the chert to these Carboniferous conglomerates. there is a mass of interstratified shales and sand­ rocks alike should be reduced to fine sediment In the former locality they are softer and more McAlester shale. Shale, sandstone, and clay stones having a total thickness of nearly 2000 feet. by the Cretaceous sea which eroded them. ferruginous. Sandstone beds of considerable constitute this formation. Its thickness is esti­ Approximately 800 feet of the lower part of this From the conglomerate at the base to the top thickness occur near the base of the formation in mated to be nearly 2000 feet, and the total thick­ formation occur in the central part of the Lehigh of the formation against the Groodland limestone the northwest corner, and associated with them ness of the shales is nearly ten times that of the basin in the Atoka quadrangle. This group of the Trinity formation is the same fine, friable sand, are local beds of thin, impure limestone. In sandstones. The shales are laminated and are strata has been named the Boggy shale because of which breaks down readily into loose sandy soil. places the sandstone makes prominent ridges and blue and black when freshly exposed. They are its broad outcrop in the valley of Muddy Boggy Occasionally, both in the conglomerate and the hills, while elsewhere the beds can not be located chiefly clay shales, though sandy shales and shaly Creek in the Coalgate quadrangle. There are sand, silicified fragments of trees are Fossildrift. in the plain. In the northeast corner of the sandstones occur interstratified with them. Two probably in the formation not less than 20 sand­ found, which were originally driftwood wood- Atoka quadrangle and in the southeast corner of local beds of sandstone in the lower half of the stone beds, ranging from thin strata to beds about swept into the sea from the shore. The Trinity the Coalgate quadrangle west of the great fault, formation, separated by nearly 400 feet of shaly 50 feet in thickness and separated by shales which formation extends continuously in broad outcrop Atoka westward and southward from this region into siliceous shell limestone, and ironstone segrega­ as are similar strata toward the base of the a vertical position. In this case the forces caus­ central Texas, where its broad areas in the region tions and concretions, aggregating approximately formation. ing the dislocation are considered to act chiefly in of Trinity River have given the formation its 140 feet. Ninety feet of the formation The outcrop of the lower and more sandy a vertical direction and the rocks above the fault name. from the base upward is of sandy clay deposits is usually occupied by forest, while that plane move down with respect to the rocks -.-, . -, . -,. concretions. Goodland limestone. Next -above the Trinity snale with some ferruginous limestone of the upper part is occupied by prairie land beneath it. The effect is termed normal faulting. formation there is a massive white limestone about segregations and ironstone nodules. East of Caddo interspersed with clumps of timber and open All these kinds of deformation have affected pre- 25 feet thick. The outcrop of this white lime Hills these beds crop in the lower slopes of hills wood. Cretaceous rocks of the Atoka quadrangle and stone is continuous across this quadrangle, bear­ and in flat prairie land near the north border of occurred long prior to Cretaceous time. ing generally east and west. Like the other the formation. West of Caddo Hills they form CORRELATION OF CBBTACBOUS FORMATIONS. The composition of the rocks now exposed in Cretaceous formations it dips at a very low angle broad tracts of generally flat country across the The change in the nature of the Cretaceous this region indicates that no elevation of the strata toward the south and makes cliffs and terraces valley of Blue River besides occurring in the strata from Indian Territory southward through into prominent land occurred between the Cam­ above slopes of the friable Trinity sand. Soft lower slopes of hills near the west border of Texas is such that it is necessary to use different brian and lower Carboniferous. Near the begin­ shales form the next formation above and these the quadrangle. Above these sandy layers are names for the formations deposited during the ning of upper Carboniferous time the are easily eroded, exposing quite broad tracts of friable sandstone beds 20 to 30 feet in thickness. western part of the Arbuckle region SIftES 01 the fla't Goodland limestone between the valleys In many places these beds are seen to be false Correlation table of Cretaceous formations. i x i j. i J i 7 , during upper was elevated to land and in part-1- to ouscarbonifer- time. of the larger tributary streams flowing north bedded, alternating with and including deposits NAMES USED IN THIS FOLIO. NAMES USED IN THE AUSTIN FOLIO. mountainous conditions. The Cam­ toward Blue River and Clear Boggy Creek. of sandy clay. These local beds are succeeded Eagle Ford formation. brian, Silurian, Devonian, and lower Carbonifer­ The Goodland limestone is a representative, in by bluish shell limestone strata separated by Silo sandstone. ous rocks, aggregating 8000 to 10,000 feet, were part at least, of several formations which occur friable shales. The limestone layers are hard Buda limestone. thus elevated and folded, and their erosion pro­ in the lower Cretaceous in central Texas, from and usually semicrystalline and upon weathering Bennington limestone. Del Rio clay. duced extensive Carboniferous limestone conglom­ .which region to Indian Territory it is continu­ turn yellowish brown or reddish. The calcareous Bokchito formation. erates bordering the uplift. Similar chert con­ Caddo limestone. Georgetown limestone. ously exposed. matrix and the oyster shells are usually of equal Kiamichi formation. glomerate deposits occuring at intervals through A bed of oyster shells is usually found at the hardness, so that the latter weather in sections on Edwards limestone. several thousand feet of upper Carboniferous strata base in contact with the Trinity sand. Higher the face of the rock. The limestones project in Groodland limestone. Comanche Peak limestone. contiguous to the west end of the Ouachita Moun­ in the limestone there are numerous fossils com­ many places as ledges and bowlders, but the Walnut clay. tains, where a thick chert and flint formation of Grlen Rose formation mon to the Comanche series of the lower Creta­ shales are rarely exposed. These beds with lime­ Trinity sand. Travis Peak formation. Silurian age is exposed, indicate that a part of ceous in Texas. stones at the top and base vary in thickness from the Ouachita Range also was elevated into land Typical exposures of this limestone occur at 10 to 20 feet. Finally, at the top of the forma­ same geologic time in the two regions. The for­ during upper Carboniferous time. Goodland, on the St. Louis and San Francisco tion, there are about 50 feet of sandy and clay mations named in this folio or their equivalents At the close of, or shortly after, the Carbonif­ Railroad in southeastern Choctaw Nation, and shales and locally friable sandstone strata. It have been traced continuously from the Atoka erous period the Ouachita and Arbuckle regions

as the first of these limestones to be described has been observed that these sandstone Cross*bedded quadrangle in Indian Territory to the Austin were entirely uplifted into land and the rocks were from this locality, the name Goodland has beds in places are cross bedded, indicat­ sandstones. quadrangle in central Texas and the accompany­ folded and faulted as now found. The length of been applied to the formation. ing variable currents in the waters during their ing table is introduced to show the correlation of time required for the production of these struc­ Kiamiclii formation. Lying upon the Good- accumulation. In the clay strata and in some of strata. tures is not known. It occurred however, between land limestone there are thin layers of slightly the iron and lime concretions there are many the Carboniferous and Cretaceous periods and NEOCENE (?) GRAVELS. siliceous limestone with a thin stratum of shale fossils with the original shell, and in some cases most probably ended long prior to the transgres­ marl interstratified. These together are but a the nacreous luster, still preserved. There are scattered deposits of coarse, hard, sion of the Cretaceous sea. The almost universal few feet in thickness and are not usually exposed Bennington limestone. The Bennington lime­ well-rounded pebbles, 1 to 4 inches in diameter, lack of local coarse material, even at the base of in the flat land immediately above the floor of stone is at the top of the lower Cretaceous in this occurring in many places in this region, the Trinity sand, which is the beach deposit, the Goodland limestone. Blue clay marl about region. In the Texas region this formation is and at various altitudes from the hill- furfVceia1d , ,, deposits of would indicate that the land was low and had 30 feet thick succeeds the thin, shaly represented by from 80 to 100 feet of calcareous tops to the present stream valleys. little relief at the time of the encroachment of strata and then follow approximately shell bedsln" fossiliferous clays. Coming northward these clays These gravels are composed chiefly of the Cretaceous sea. 20 feet of blue clay marl and oyster- gradually thin and change to limestone and clay pebbles of quartz and quartzite, many of which Since Cretaceous time the whole region has shell beds interstratified. These shell beds usually interstratified and then into a hard limestone have become rough or pitted upon the surface been uplifted and but slightly tilted southward are less than a foot in thickness. They are com­ which occurs in southern Indian Territory and and are partly disintegrated through long expo­ without folding. This late oscillation of the land posed almost entirely of oyster shells ranging the Atoka quadrangle. sure. Such deposits are found in this quadrangle and the progress of recent denudation has already in size from very small to 3 inches in length, In the Atoka quadrangle the Bennington lime­ upon the eroded edges of Carboniferous and been discussed under the heading "Topography." cemented by marly lime. The more or less indu­ stone is generally massive dull-blue limestone 10 Silurian rocks, and farther south upon Cretaceous rated beds are generally exposed as ledges or feet or less in thickness. It is composed in large rocks. They are too thinly spread over the sur­ STRUCTURE SECTIONS. slabby fragments forming a continuous outcrop part of countless specimens of a peculiar small face to be mapped, and it is not believed that The folding and faulting which have occcurred at the top of the formation. oyster, Exogyra arietina, by which name the clays they now occupy their original position, since in this district are graphically shown on the Struc­ The Kiamichi formation, with other Cretaceous representing this formation in central Texas have they occur distributed at various levels. The ture Section sheet. The sections represent the deposits occurring in the Atoka quadrangle, crops been known. Locally there are thin deposits of age of these deposits is problematic. Consider­ earth cut vertically along the lines shown on the across the southern portion of the Choctaw Nation. marly limestone resting upon the harder beds of able quantities of pebbles, which are found in map to a depth of 2500 feet below the level of Prominent exposures of this formation have long the Bennington which are the representative in the vicinity of Stringtown and northeastward, the sea, and the face of the cut presented to view. been observed in the plain of Kiamichi River age, in part at least, of the succeeding limestone came probably from the conglomerate member at By taking the McAlester formation, which is near the St. Louis and San Francisco Railroad in formation in central Texas. A good exposure of the base of the Trinity sand which is considered shown in strong color in Section BB, a fair idea of southeastern Choctaw Nation and for this reason this rock occurs near the road one mile northwest of to have once spread over extensive areas north the folding in the Lehigh syncline may be obtained. the formation has been so named. Bennington. The Bennington limestone, although of its present border. Some of these gravels at This formation, if projected upward toward the Caddo limestone. This formation consists of a thin formation, is generally exposed in low bluffs least are of much later age than the Cretaceous, east, would approach the great fault several thou­ clay, calcareous marls interstratified with white and terraces, the rocks above and below being since they are found scattered over the edges of sand feet above the present surface of the land. or yellowish marly limestone, and semicrystalline friable and more easily eroded. West of Robbers the Cretaceous formation in the southern part of Section CC illustrates the extensive normal fault­ limestone, making a section about 150 feet thick. Roost, near the border of the quadran- the quadrangle and in northern Texas beyond ing in the granite and in the Silurian and Carbon­ The marly beds are thickest near the base, the gle.1*1 it crops in' the,1 crestif ot some rem- cappingLimestone the valley of Red River, and they are tentatively iferous rocks; also the low-dipping monoclinal , , n /./-tii- Caddo Hills. lower 60 feet being composed chiefly of clay marls. nental buttes, and south ot Caddo it regarded as Neocene. Their relation to the Ter­ Cretaceous rocks farther south. Above this there are 20 to 30 feet of lime marls forms the cap rock of Caddo Hills. It is the sur­ tiary peneplain i£ not known. Section AA illustrates the axial pitch of the with some chalky white limestone strata inter- face formation of a considerable area of flat fertile eastern end of the flat anticline in the northwest­ GEOLOGIC STRUCTURE. bedded. In this member are some oyster-shell land in the southeastern part of the quadrangle. ern corner of the quadrangle. beds similar to those at the top of the Kiamichi Silo sandstone. Only the lower part of the All stratified rocks, especially those of broad formation. Higher still in the formation the Silo sandstone occurs in the Atoka quadrangle. extent, were deposited beneath the water in STRUCTURAL PROVINCES. marly beds become thinner, while the limestones The whole formation is estimated to be approxi­ nearly flat positions. Their elevation into land The rocks of the Atoka quadrangle have been increase in number and thickness until near the mately 500 feet thick in north Texas adjoining and their tilting, folding, and breaking are due to affected by varying forces producing distinct top the marl occurs as thin strata or mere partings Red River, the nearest locality to the Atoka quad­ forces of deformation within the earth. Simple forms of structure occupying separate areas. between the limestone beds. Finally, at the top rangle where it is completely exposed. tilting or warping of the strata in one direction These areas are but small parts of structural of the formation, there is a bed of oyster shells The Silo sandstone is the basal formation of is termed nionoclinal folding. Bending of the provinces which extend toward the north, east, similar to those occurring below and at the top of the upper Cretaceous, and, like the Trinity sand, rocks upward into arches and domes and down­ south, and west, and which coincide practically the Kiamichi formation. it was deposited near the shore of the ward into troughs and basins is termed anticlinal with the geographic provinces referred to under The harder limestone at the top of the forma­ CretaceousC\ j_ sea, ibut j_ upon a very slightlyi 1 j_i ofBasal the sandupper and synclinal folding respectively. Such struc­ ' r . « Cretaceous. the heading "Geography." In the discussion of tion projects as a ledge in the escarpment which eroded surface. It consists ot tine tures are considered to be produced by compres- the structure it will be convenient to use the it produces in the vicinity of Caddo and in many brown sand and sandy clays interstratified. The sive forces acting approximately parallel to the same titles applied there. places east and west across the quadrangle. sandy beds are thickest in the lower middle part surface of the earth, and crumpling the nearly Many valleys have their heads in the escarpment of the formation, and occasionally extend to the flat rocks into folds as the leaves of a book may OUACHITA UPLIFT. and some cut across it, and the streams in these base, although the basal beds are usually clays be folded by the hands. If the forces producing This uplift is limited on the north by the valleys make fresh exposures of the limestone and and sandy clays. Some of the sandstone beds such folding cause sufficient movement, the rocks northern border of the Ouachita Range, which marl. The Caddo formation throughout contains contain segregations of brown siliceous iron ore may be broken and the strata upon one side may extends through southwestern Arkansas and great numbers and many kinds of marine fossil which occur as stony fragments upon the surface be thrust past those upon the other, producing southeastern Indian Territory to the vicinity of shells. where the including sand has been removed. what are called thrust faults or overthrusts. The Atoka. The folds in the central portion of the Bolccliito formation. This formation is so Toward the upper part of the formation as it planes of such overthrusts vary in position from range, both in western Arkansas and in eastern named because of its splendid exposures on occurs in this quadrangle the sands are finer, less horizontal to an angle of 45° from the horizontal, Indian Territory, bear nearly east and west. Bpkchito Creek in the vicinity of the village of abundant, and more generally disseminated in the and the rocks above this plane move upward with Near the western end of the uplift the folds, the same name. It is composed chiefly of clay clays, making deposits of siliceous clays or respect to the rocks beneath it. Another form of both large and small, curve gradually toward the and sandy clay, with beds of friable sandstone. argillaceous sand not so distinctly stratified dislocation may occur along planes that approach south and disappear beneath a covering of flat- lying Cretaceous sediments. The uplift may be ARBUCKLE UPLIFT. the rocks had been disturbed, nearly 9000 feet of 'coal is highly bituminous and is used chiefly for divided longitudinally into two belts, northern The western part of this uplift is coincident Cambrian, Silurian, and lower Carboniferous rocks steam purposes. ! . and southern. The southern portion is worn with the Arbuckle Mountains. The rocks of the rested normally above the granite. Now they The upper coal in the McAlester shale is known down and in part concealed by the Cretaceous eastern part have been worn down to the level of are steeply tilted and fractured, approaching the locally as the Lehigh bed on account of its most deposits. The northern half of the uplift in the Cretaceous erosion plain, and are in part con­ granite abruptly at various angles. The flat Cre­ extensive development at the town of Leh. h coal Indian Territory contains a great number of inter- cealed at the southeastern border by the fiat Cre­ taceous sediments conceal a large part of the rocks Lehigh, 3 miles south of Phillips. This b*d-'g "* lapping, nearly parallel, narrow folds, which have taceous deposits. upon the southern side of the anticline. coal runs regularly about 3-| feet in thickness and, been formed by northwestward thrusts and in During early Carboniferous time the rocks in the as far as known, is without shale partings. many instances have been overturned and region of the Arbuckle Mountains were flat and RED RIVER MONOCLINE. In the northeastern part of the quadrangle broken. were covered by the sea. At the beginning of Coal That part of the Red River Plain in the Atoka rocks at the horizon of the Lehigh coal crop in In Indian Territory this greatly folded belt is Measures age the western part was uplifted and quadrangle is confined to the area of Cretaceous a rough hilly country and dip 40° to 60° NW. limited abruptly on the north by a very extensive folded into a mountainous country and the soft rocks. The Cretaceous rocks were deposited after The coal has not been prospected at this place fault. This great displacement, called Choctaw lower Carboniferous strata were eroded and again the folding of the older rocks in the northern part and its condition is not known. Southwestward the Choctaw fault, separates the more fault- transported into the sea. More than this, streams of the quadrangle and the sediments were spread the dip decreases to approximately 25° in the gently folded northwestward-dipping rocks on cut down into harder Silurian and Cam- Unconformity,, across their worn edges, as has been shown in the axial part of the basin northwest of Atoka. On the northwestern side from the overthrust south­ brian rocks in this mountainous district Sppfr car- discussion of the stratigraphy. Since Cretaceous the western side of the basin the coal is well dis­ eastward dipping, older rocks on the southeastern and brought into the upper Carbonifer- boniferous- time this region, including the Atoka quadrangle, posed structurally, dipping to the east about 4°. side. ous sea great quantities of limestone, which formed has not been deformed but has been broadly It is actively mined at Lehigh, Phillips, and Coal- This great fault enters the northern part of the limestone conglomerates along the northern and uplifted and depressed, and the surface probably gate, the last-named place being 2J miles north of quadrangle near the Missouri, Kansas, and Texas southern sides of the uplift west of the Atoka slightly inclined. At the present time these rocks the quadrangle. Railroad, and bears nearly due south along the quadrangle. At this time the Wapanucka lime­ are uniformly and evenly tilted toward the south In physical appearance the Lehigh coal is lami­ western side of the Talihina chert ridge. The stone and many succeeding beds were formed. at the approximate grade of 40 feet per mile. nated and, in mining, breaks into good-sized cubical Silurian rocks upon the eastern side have been After the close of the Carboniferous period the blocks. Thin filaments of iron sulphide 1 i i i j» i 11 Character of thrust upward and westward o'ver the upper Car­ whole Arbuckle region was elevated, and thou­ MINERAL RESOURCES. and sulphate ot lime occur occasionally the Lehigh boniferous rocks upon the west. The Stringtown sands of feet of Carboniferous rock as well as the in the joints of the coal. It is highly shale, Talihina chert, and Standley shale, probably central mass of older limestone and granite which The mineral resources of this region are coal, bituminous, the fuel constituents of the coal being 8000 feet of strata, are not represented upon the are now exposed in the center of the uplift were granite, limestone, sandstone, and clay. Besides carbon 41.12 per cent and volatile combustible western side of the fold, having been concealed tilted, folded, and faulted. these resources there should be considered also matter 41.61 per cent. There is 13.7 per cent of by the overthrust faulting. Other thrust faults This uplift is a broad, wrinkled, and broken the soils, some of which are very fertile. Coal is ash, and 4.5 per cent of sulphur. These results of extensive displacement occur in the Ouachita anticline. The strata on both sides, including the only product that has been developed to any are from an analysis of the coal from shaft No. 5, Range near the axes of large folds parallel with many formations of Carboniferous, Devonian, and considerable extent. Building materials have at Lehigh, about 200 feet beneath the surface. the trends of the rocks. In all these cases Silurian age, dip steeply away. The central part received less attention, and clays none at all. In a The samples were taken from the commercial of faulted folds the overthrust is to Belt of faulted of the uplift is composed of several broad, shallow region generally undeveloped, as this is, and under product on cars ready for shipment. the northwest. The western ends of folds- folds. The axial parts of the anticlines, wherein such civil conditions as have existed in Indian four of these faulted folds enter the northeastern are exposed a great thickness of massive Cam­ Territory, it is probable that no mineral product GEANITE. part of the Atoka quadrangle and die out in the brian and Silurian limestone, are generally broadly would be developed except under assurances of The Tishomingo granite is exposed in an area Standley shale. The recurrence of the lower flexed; while the younger, softer, and thinner considerable profit. of about 12 square miles in the Atoka quadrangle. part of the Jackfork sandstone along three of rocks in the intervening synclines are crumpled All of the deposits of economic value in this As described above under " Geology " the granite these faults, dipping always toward the southeast, into many small folds. These synclines are broken region except granite occur in stratified rocks and is generally of rather coarse texture and is pink­ is evidence that the corresponding southern limbs and displaced in an extraordinary degree by ten­ may be definitely located in the formations which ish or reddish. It is variable, however, both in of these synclines are faulted out. sion or normal faulting which took place probably are outlined on the map. Those formations color and texture, ranging from a very coarsely In line with these faults toward the southwest during or since the folding. which contain the most profitable beds of coal, crystalline to a fine-grained rock, and from light there are corresponding northeastward pitching At the eastern end of the Arbuckle uplift one limestone, and sandstone are emphasized on the pink to almost red. narrow folds in the Talihina chert and lower part of the northern folds, called the Hunton anticline, Economic Geology sheet. Nothing very definite In parts of the area the Tishomingo granite has of the Standley shale, which would indicate that enters the northwest corner of the Hunton is known of the qualities of the clays. Special suffered crushing and faulting to such an extent these rocks were deeply buried at the time of Atoka quadrangle, pitching eastward anticline. tests are required to determine whether a clay that it can not be used successfully as a building their folding and that they have since been at an angle of 10°. The axial portion is broad will produce fire brick, or may be serviceable in stone. In such places the rock is intersected in uplifted and tilted eastward when they were and flat while the sides are sharply flexed down­ the manufacture of cement, or is suitable for other many directions by fractures which cause it to thrust up along the great fault at the west side ward and even faulted. The displacement of the purposes to which clays are adapted. Clays break into irregular small pieces upon being of Black Knob Ridge. faulted strata on each side of the fold is several occur in the Carboniferous formations in great quarried. In a large part of the area, however, hundred feet. Toward the east these faults die quantity, and it is deemed important to point out it occurs as a massive rock, so that large masses ARKANSAS VALLEY REGION. out in the Carboniferous strata, but toward the their occurrence and condition of structure, so of valuable stone could be quarried. As described under " Geography " the Arkansas west they increase and join a number of fractures that in the future those who wish may investigate The Tishomingo granite will make a handsome Valley region is a broad physiographic basin lying of the same nature. them to the best advantage. building stone and will bear a smooth polish in between the Ouachita Mountains upon the south A flat eastward-pitching syncline occurs imme­ working for ornamental purposes. This Ornamenta, and Ozark Highland on the north. It is a deep diately south of the Hunton anticline. This may COAL. granite has not been quarried in the stone< structural basin, much folded, especially on the be called the Wapanucka *- syncline > Wapanucka, There are two beds of coal of workable thick­ Atoka quadrangle though it occurs within 10 southern side. because it occupies the broad flat val- syncline- ness, both of which occur in the McAlester shale. miles of the railroad. In the Tishomingo quad­ Structurally the Arkansas Valley region is a ley of Wapanucka Creek. This syncline becomes' One occurs close to the base of the formation and rangle it has been utilized, the Chickasaw capitol direct northward continuation of the Ouachita broader and flatter eastward- until it dies out or the other about 250 feet below the top. building at Tishomingo being constructed entirely uplift, but the folds are generally natter. joins indistinctly with the Lehigh basin in the The lower bed, which is known locally as the of this stone. A new branch of the St. Louis In western Arkansas and eastern Indian JJJe^2[^ coal field. Westward it contracts by faulting Atoka coal, is about 4 feet thick and has shale in and San Francisco J&ailroad has recently been toward the axial part until it practically ceases as Territory there is a gradual change ouachfta contact both above and below. This Atoka coal at built from northern Indian Territory to Texas northward from the overturned broken uphft' a fold 6 miles west of the quadrangle. Still coal occupies the same stratigraphic across the western part of the Tishomingo granite folds into the more symmetrical structures of the farther west across the Tishomingo quadrangle it position as the Hartshorne coal, which hornecoal- area, which should induce development of the Arkansas Valley region. In the western part occurs in parts along a faulted zone. The south­ is worked extensively in the eastern part of the granite industry. of the Ouachita uplift the change is more ern limb of the Wapanucka syncline in the Atoka Choctaw Nation. It has been worked in this LIMESTONE. abrupt. quadrangle is very extensively fractured and dis­ vicinity at what is known locally as the Hickory The folding of the Arkansas Valley region in placed by a system of faults. In each case the Hill mine, which is near the south end of the The Wapanucka limestone is the most import­ eastern Indian Territory decreases gradually displacement is downward toward the northeast. Lehigh basin, 4J- miles south of Lehigh. The ant formation in this quadrangle for the produc­ northward into the very slightly undulating struc­ Where two or more of these faults having dis­ coal at this mine dips to the northeast about 5° tion of building stone. The formation crops in ture of the immediate valley of the Arkansas placements in the same direction join, the com­ It has been prospected at many places east and ridges from the northwest corner of the quadran­ River. The folds gradually decrease in intensity bined throw is very great. One mile east of the west of the mine in the southern part of the gle southeastward to the vicinity of Boggy Depot. westward and, one after the other, merge upon border of the quadrangle Carboniferous shales are basin. The position of this coal is immediately This limestone occurs in ample abundance for any the northern side into the monoclinal structure brought down in contact with lower Silurian or above the Hartshorne sandstone and it should be purpose to which it may be applied. The beds of the Prairie Plains. Cambrian limestone in a displacement of probably found beneath the soil approximately upon the of purer limestone occur in the upper part of the The Lehigh syncline represents the extreme 4000 feet. Two miles south of Wapanucka the contact between this sandstone and the succeed­ formation and may be utilized in the manufacture southwestern limit of the Arkansas Valley struc­ displacement is even greater. At this place nearly ing McAlester shale. At the southern end of of lime. These beds are rather hard, and may be ture. From a southwestward course, parallel to the whole Cambrian and Silurian sec- Extensivec , . the basin the coal dips toward the north at an obtained in dimensions which render Wapanucka the general folding of the region farther northeast, tion of about 8000 feet is concealed by faultin«- angle of about 10°. Northwest of the Hickory them serviceable for foundations, bridge J^UM" it turns due south into the Atoka quadrangle and cumulative faulting. Hill mine the dips vary from 4° to 6°. In the piers, and for general building pur- mgstone> comes to an end in a deep, unsymmetrical, spoon- The long granite area which extends northwest­ northeastern part of the quadrangle the rocks at poses. A bed of fine white oolitic limestone like basin between the Ouachita Mountain and ward from the vicinity of Boggy Depot occupies this horizon dip 60° to 80° to the northwest, but occurs near the top of the formation, well situated Arbuckle Mountain regions. The form of this the axial part of an anticlinal fold, the sides of the coal is not known to occur. If it should be for quarrying, in the northwestern part of T. 1 syncline has been affected by the forces which which have been faulted in an extraordinary found, however, it probably could not be profita­ S., R. 9. E. This rock is moderately hard and produced the contiguous structures of the Ouachita manner. This fold will be called the Belton bly mined on account of the steep dip of the rock. will make an excellent building stone. The and Arbuckle uplifts. On the eastern side the anticline from the town of Belton which The coal as it occurs at the Hickory Hill middle and lower beds contain chert Road ballast. rocks have been tilted steeply by the overthrust is located upon it 5 miles west of the ciine°expos-Belton anti- mine is laminated and, in mining, breaks into and are interstratmed with chert and , .-p., , , ing granite. faulting. On the southwestern side the trends of quadrangle. Ihe contacts between the cuboidal blocks. In the «joints of the Character.,. , of. sandy layers, and they may be used profitably for the rocks in the syncline conform rudely to the Silurian and Cambrian limestones and the granite,' coal and in places between the laminae vaSm^nm road material. The Missouri, Kansas and Texas folding in the eastern portion of the Arbuckle with the exception of one instance in sec. 28, T. 3 there are thin filaments of iron sulphide, mine' Railroad has established a crushing, plant at Chick- structure. S., R. 9 E.; are along faults. Originally, before and near the surface there is sulphate of lime. The achoc switch, near the southwest corner of the Atoka 8

M<3Ales,ter quadrangle, and has utilized very exten­ is utilized in the construction of foundations of The structure of the formations in which the sand and clay and upon the inclination' of the sively the Wapanucka limestone and chert occur- business houses. In the eastern part of the clays occur has been sufficiently explained, it is surface. The soil of the clays is generally com­ ing near there for its road ballast. Lehigh basin the rocks are steeply upturned and believed, to show where they may be profitably pact and occupies flat areas, best adapted to The Goodland limestone is a nearly pure many of the beds contain fragments of angular exploited. meadow and pasture. The sandy loams rest upon massive bed of white limestone well situated and chert, so that they are not well adapted for build­ the low slopes of hills and gentle swells made by Structurally disposed for use, but it is generally ing. The thinner and harder beds in the Savanna SOILS. the sandy members of the formations and consti­ too soft and weak for a good building stone. It is and Boggy formations will make good paving The soils in the Atoka quadrangle are of great tute the best tillable soils. considered an excellent lime-producing Lime= roduc_ flags. All of the sandstone beds of these forma­ variety, ranging from an almost barren stony soil, The Trinity sand produces a loose sandy soil rock and is situated upon the border lng rock- tions except the conglomerates in the eastern part serviceable only for grazing, to the most fertile or simply a loose sand without perceptible ele­ of the extensive timber belt of the Trinity sands, of the Lehigh basin are fine grained and yellow­ river bottom and black marly upland. The soils, ments of soil. In places where the country is where fuel for burning lime is abundant. ish or reddish brown. The cementing material excepting those in the stream bottoms, are resid­ almost perfectly flat this formation makes a Certain beds of the Arbuckle, Viola, and Hun- which binds the sand is composed either of silica ual; that is, they are derived directly from the dis­ light loamy soil, moderately fertile, which is best ton limestones are quite crystalline and hard, but or of silica and oxide of iron together; in the integrating rock of the formations lying beneath adapted to the production of fruits and Forest- they are for the most part steeply tilted, folded, lighter-colored stones it is chiefly silica, while in them. The classification of the soils therefore vegetables. In the more rolling part covered flat land. and broken, so that they can not be utilized sue- the darker it is in large part iron oxide. Both would correspond practically to the classification and in most of the flat lands, the sessfully as building stone. Near the northwest stones are very durable in color and strength. of the rock formations. Trinity sand area has still upon it the forest, its corner of the quadrangle, however, parts of the All of the formations composed of hard rocks best product, which should be carefully preserved. Viola and Hunton limestones are nearly flat, and CLAY. Arbuckle limestone, Simpson formation, Viola The Goodland limestone produces a black some of the harder beds may serve for common Clay and shale are the most abundant of the limestone,' Hunton. limestone,' "Woodford Grazing_ . calcareous clay soil, but, owing to its outcrop in building purposes. Some of the limestones in rocks which occur in the Carboniferous formations chert, TaKhina chert, Jackfork sand- lands< terrace escarpments and steep slopes, the soil is these formations are cherty and others are sili­ in this region. In the Wapanucka limestone and stone, and Wapanucka limestone because of removed as fast as formed, except in occasional ceous, and they would make road metal of high Hartshorne sandstone they occur in thin strata their narrow outcrop or rugged surface, produce small flat areas between the valleys. The suc­ quality. and are of local extent, but in the other forma­ stony soils, and, with the exception of very limited ceeding< & Kiamichi,' Caddo,' and Benning-& Fertile_ ... black., , tions they occur in great abundance. These beds areas, are fit only for grazing lands. ton limestones form black calcareous soils' SANDSTONE. vary in quality from very sandy strata to purer The Tishomingo granite lies in a nearly level clay soils which are very fertile. These lands are Beds of sandstone occur in the Savanna and argillaceous, finely laminated clays. plain, but for the most part its soils are very thin generally smooth, though rolling. The Bokchito Boggy formations which may be serviceable in Associated with coals, usually at their lower and contain an admixture of loose sand from the formation, being composed of ferruginous sands many ways as building material. Savanna contact, are beds of almost structureless blue clay. Trinity formation, which recently covered it. and clays with occasional limestone layers and Many of the beds, and especially some |oodsbu"ied» These beds are generally thin, but the clay may The Caney shale is friable and calcareous, and forming a more or less hilly or rolling country, of those of the Savanna formation, pro- lng stone' prove valuable in the manufacture of probably phosphatic, especially in the lower part. produces moderately fertile reddish or Fruit lands. duce excellent building stone. The Savanna stone fire brick. These and other clays asso­ This shale land is flat or gently rolling, and con­ brownish loams, which are best adapted is yellowish or reddish brown, and the beds are ciated with the coals may be utilized more tains the most fertile soils in the northern part of to fruit growing. The Silo formation makes a evenly stratified and moderately hard. This stone economically than other beds because of their the quadrangle. The country of the Standley reddish and brown sandy soil resembling that of is quarried successfully in large quantities for proximity to fuel. shale is generally smooth, but its soil is not very the Trinity formation. It is more fertile, how­ dwelling and business houses at South McAlester, The clay shales usually vary in hardness with fertile. ever, and, besides producing the usual crop of in the adjoining quadrangle, where the Missouri, the amount of sand and other impurities contained The Atoka, Hartshorne, McAlester, Savanna, cotton and grain, it is admirably adapted to the Kansas and Texas Railroad crosses the formation. in them. The more impure varieties are almost and Boggy formations produce a variety of clay cultivation of peaches and small fruits, especially The brownish sandstone at the base of the Savanna stony in hardness, while the purer kinds are fri­ and sandy loamy soils. The relative fertility of grapes. formation is quarried in the town of Lehigh and able and upon slight weathering are often plastic. these depends upon the proportionate mixture of February, 1902