Purpose of Report
It is the aim of this paper to record pertinent features of classification and nomenclature of rocks belonging to the Pennsylvanian System in Kansas. This subject was reviewed by me in detail (Moore, 1936) in a report of the Geological Survey which traced the evolution of each stratigraphic division, including many names which have been abandoned, as well as those now generally employed. Three reasons may be cited for preparation of a new report defining the division of Pennsylvanian rocks which are recognized in Kansas and describing them briefly. (1) Demand for the 1936 report on Kansas Pennsylvanian rocks has been such that it has long been out of print; an up-to-date discussion of the subject is needed, not exactly as replacement of the older report, for the new one is not simply a new edition, but as supplement to it which will satisfy needs of almost anyone interested in the subject. (2) In May 1947, an interstate conference on Pennsylvanian classification in the northern midcontinent resulted in agreement by the geological surveys of Iowa, Kansas, Missouri, Nebraska, and Oklahoma on definitions of major and minor rock divisions belonging to this system which are recognized to extend from one of these States into another. The classification thus adopted involves some changes of official usage of the Kansas Geological Survey, and it is desirable to publish a statement of all such changes, with explanation. (3) The years 1936 to 1949 have brought a number of additions and a few revisions of names applied to minor rock units of the Pennsylvanian sequence in Kansas. These have already been incorporated in survey publications, but they have not been treated in a systematic report on Pennsylvanian rock units.
Nature and Distribution of Pennsylvanian Rocks in Kansas
Deposits belonging to the Pennsylvanian System which occur in Kansas are predominantly characterized by features of sedimentation on stable platform areas of the continent, as contrasted with sedimentation in the strongly subsiding troughs called geosynclines. Rock formations of the comparatively even-surfaced platform region are mostly thin but they have remarkable lateral uniformity throughout large areas. Marine deposits laid down in very shallow seas are very important components of the Kansas geologic section. Geosynclinal deposits, such as are well-developed in the southern Oklahoma region and in west-central Arkansas, are distinguished by thickness of formations measured in hundreds or thousands of feet and by general prominence of sandstone and shale deposits. Individual rock units are not traceable commonly for long distances because they have lenticular form or they grade laterally into different sorts of deposits. Marine strata occur in the geosynclines, but they are less prominent than nonmarine beds.
The Kansas Pennsylvanian rocks may be compared to a small stack of many-colored sheets of paper ranging in weights from thinnest onion-skin to cardboard. Each sheet of some specified color represents a certain kind of rock, such as black platy shale, light-gray calcareous shale, coal, a particular sort of limestone, and so on. The extreme relative thinness of the sheets as compared to their lateral dimensions suggests the small vertical measurements (ranging from less than 1 foot to not more than 25 feet generally) of Pennsylvanian rock units which can be traced 100 to 400 miles along the outcrop and similar distances at right angles to the outcrop underground. Of course, there are irregularities. Some layers vanish here and there, and they may show local pinching or swelling in the area where they persist. These are features which we should expect to find. The outstanding character of the Pennsylvanian rocks north of Oklahoma, nevertheless, is stratigraphic regularity and this makes possible application of the same classification and nomenclature of divisions (with very minor variations) throughout the States of Kansas, Missouri, Iowa, and Nebraska.
Pennsylvanian formations form the bed rock of eastern Kansas next below the soil, alluvium of stream valleys, glacial deposits (in northeastern Kansas), unconsolidated, wind-blown materials (loess), and the like (Fig. 1). In this area are many exposures of the Pennsylvanian bed rock, as in the walls of stream valleys, highway and railway cuts, and quarries. Collectively, the region in which the Pennsylvanian strata are actually exposed and in which they are concealed only by the unconsolidated mantle of soil and other surficial materials, is called the outcrop area of these rocks. It includes approximately the eastern one-third of Kansas, reaching westward to the vicinity of the Flint Hills belt, which extends across the State from Nemaha County on the Nebraska line to eastern Cowley County on the Oklahoma line. All of the territory in Kansas east of the Flint Hills belongs to the Pennsylvanian outcrop area, except a few square miles in the southeastern corner of the State, where Mississippian rocks occur next below the surface.
Figure 1. Outcrop of Pennsylvanian rocks in Kansas, and parts of adjoining states. The map shows main divisions termed Desmoinesian, Missourian, and Virgilian.
The trend of outcrops (strike) of individual Pennsylvanian units in Kansas is mostly south-southwest. The rocks dip gently westward at an average rate of approximately 25 feet to the mile, and deposits belonging to this system underlie all of central and western Kansas. In this area where the Pennsylvanian is buried by younger formations, the thickness of the latter (and hence the depth to the top of Pennsylvanian deposits) ranges from a featheredge to nearly 4,000 feet. Average thickness of Pennsylvanian rocks at the outcrop in Kansas is approximately 2,500 feet.
The hard Pennsylvanian rocks, mostly limestone and sandstone, cap uplands and form escarpments or benches, some of which are prominent and can be traced for many miles. The general front of escarpments faces eastward. The weak Pennsylvanian rocks, chiefly shales, form gently rolling plains or lowlands, and commonly they occur in the lower slopes of escarpments beneath the protecting cap of hard strata which make the top of the escarpments.
The limestone and shale divisions of the Pennsylvanian System, together with less important sandstone and coal beds, are arranged in alternating succession. The limestone and part of the shales are marine; some of the shales, the coal beds, and most of the sandstones are nonmarine. These rocks occur in constant sequences which permit recognition of cyclic sedimentation. The cycles represent repeated inundations of the Kansas region by the Pennsylvanian shallow seas, some submergences being more extensive and long-enduring than others. These features have bearing on classification of the Pennsylvanian rocks, as discussed briefly in a later part of the report.
Previous Studies of Pennsylvanian Rocks in Kansas and Neighboring States
A beginning of systematic stratigraphical work on rocks of the Kansas region which now are classed as Pennsylvanian was made when Meek & Hayden (1859) studied the Pennsylvanian section of the Kansas River Valley, and B. F. Mudge (1866), first State Geologist of Kansas, described Carboniferous strata exposed in eastern Kansas. Swallow & Hawn (1865) and Swallow (1866) constructed a composite section of Pennsylvanian rocks observed in Kansas, in which geographic names such as Fort Scott, Stanton, and Plattsburg were first applied to stratigraphic divisions. In Missouri, work on the Pennsylvanian section exposed along the Missouri River was done by G. C. Broadhead (1866). During the 1860's the Geological Survey of Iowa made a general study of the so-called Coal Measures which are exposed in the central and southwestern part of that State (White, 1870), and Meek (1872) published descriptions of Pennsylvanian strata and fossils of eastern Nebraska.
No work of importance was done during the following two decades, but beginning in 1890, Haworth and associates of the reorganized Kansas Geological Survey made several traverses across the Pennsylvanian outcrops along selected lines and introduced many new stratigraphic names. Correlation of these sections showed that some strata were differently named in the various sections. A classification was developed (Haworth, 1894, 1895; Haworth & Kirk, 1894) in which all of the Pennsylvanian deposits were assigned to named groups and formations. In Iowa, surveys were made of counties in which Pennsylvanian rocks are exposed and various stratigraphic units were named. Some work was done on coal resources of Missouri and first efforts to classify Pennsylvanian rocks in northern Oklahoma are recorded in the work of Drake (1897).
The most important publications dealing with Pennsylvanian rocks in the northern midcontinent region in the period from 1900 to 1909 were a bulletin (Adams, Girty, & White, 1903) of the U. S. Geological Survey on Upper Carboniferous rocks of Kansas, and a summary of the stratigraphy of these rocks published by the Kansas Geological Survey (Haworth & Bennett, 1908). These describe the Pennsylvanian formations then known, and give observations on their paleontological characters (Beede & Rogers, 1908).
The years 1910-19 witnessed activities in Pennsylvanian stratigraphic investigations throughout most of the midcontinent area. Chiefly important were reports by Hinds (1912) on coal and by Hinds & Greene (1915) on stratigraphy of Pennsylvanian deposits in Missouri. The latter paper was accompanied by paleontological discussions on invertebrates by Girty (1915) and on plants by White (1915). In Oklahoma, first effort to describe and classify Pennsylvanian strata in the northeastern part of the State (Ohern, 1910) and a series of oil and gas surveys by Federal geologists laid the foundation of classification and nomenclature of these rocks in northern Oklahoma. Summaries of the Pennsylvanian stratigraphy of Kansas (Moore & Haynes, 1917, pp. 78-107; Moore, 1920), which include some modifications of Haworth's classification and incorporate features derived from the work of Hinds & Greene, were published. The first modern work on Pennsylvanian rocks in Nebraska was recorded in a paper by Condra & Bengston (1915).
In the 1920's, work deserving special mention is the first comprehensive report on Pennsylvanian rocks of Nebraska (Condra, 1927), in which numerous subdivisions of previously defined formations were named. Although serious errors in interpretation of some units were made, especially in correlating the Platte Valley section, Condra's studies indicated the great persistence of many minor divisions of the rock succession and by introduction of formal nomenclature for them he laid groundwork for more detailed and precise stratigraphy of midcontinent Pennsylvanian deposits.
Partly from the impetus of Condra's work and partly from interest in exploring evidence of cyclic sedimentation, study of Pennsylvanian stratigraphy was accelerated in the midcontinent area in the 1930's. In Kansas, stratigraphic sections and maps were gathered from oil companies and other sources for use in compiling a State geologic map (Moore & Landes, 1937). Field work was done by Moore, N. D. Newell, J. M. Jewett, W. H. Schoewe, M. K. Elias, and other survey members in every county having Pennsylvanian outcrops. Classification of rocks belonging to the system was revised in several ways, as by recognizing major time-rock divisions bounded by disconformities, by changing the assigned limits of some main lithologic units (groups) and by applying results of studies on cyclic sedimentation to definition of many formation and member units (Moore 1932, 1936; Newell, 1935, Jewett, 1933; Jewett & Newell, 1935).
In Nebraska and Iowa, Condra and associates (Condra, 1930, 1933, 1935; Condra & Upp, 1933, 1933a; Condra & Reed, 1937; Condra & Scherer, 1939) published several papers giving information and new conclusions as to identification and stratigraphic classification of rock units, mostly of Missourian and Virgilian age. In 1932, D. G. Stookey and M. L. Thompson began studies of the Desmoinesian rocks of Iowa, working under direction of A. C. Tester, but results are unpublished except for a paper by Thompson (1934) on fusulinids from some of the lower beds. Detailed work on upper Desmoinesian and lower Missourian strata of Iowa was carried on by L. M. Cline during the years 1935-1941. Some of the stratigraphic results, including correlation of Iowa and Missouri units, have been reported by Cline (1941). McQueen & Greene (1938) published a comprehensive report on oil and gas exploration in northwestern Missouri, with which a chart showing lithologic features and classification of the Pennsylvanian column of that State was offered. Several papers on stratigraphy of Pennsylvanian rocks in Oklahoma were published, and through collaboration of oil company geologists, numerous subsurface cross sections, showing the nature and correlation of Pennsylvanian rock units in Oklahoma and Kansas, were prepared.
The years from 1940 to the present have been somewhat less productive of advances in knowledge of northern midcontinent Pennsylvanian rocks than some previous equal periods, largely because of conditions imposed by World War II. In this period, however, two reports of continent-wide scope (Moore et al., 1944; Cheney et al., 1945) which treat classification and correlation of Pennsylvanian rocks in the midcontinent states have been issued. In less detail, the Pennsylvanian deposits were reviewed also in a survey of midcontinent stratigraphy (Dott, 1941). An important paper by Cline (1941) gives results of his studies on Pennsylvanian rocks in Iowa with indication of equivalent rock units in Missouri. A comprehensive summary of Pennsylvanian classification in Nebraska was published in 1943 by Condra & Reed and a similar one for Kansas, in 1944, by Moore, Frye & Jewett. Studies of upper Desmoinesian (Jewett, 1941, 1945) and lower Virgilian (Bowsher & Jewett, 1943) rocks in Kansas contain important new data and work in northeastern Oklahoma by Oakes (1940) makes additions to knowledge of Pennsylvanian rocks in this area.
A recently published paper (Moore & Thompson, 1949) proposes recognition of three main divisions of the Pennsylvanian rocks, each composed of two lower-rank divisions, as follows: Lower Pennsylvanian rocks called the Ardian Series contain the Springeran Stage, below, and the Morrowan Stage, above; Middle Pennsylvanian deposits called the Oklan Series include the Atokan Stage, below, and the Desmoinesian Stage, above; Upper Pennsylvanian strata named the Kawvian Series are divided into the Missourian Stage, below, and the Virgilian Stage, above. This classification differs from prevailing usage mainly in emphasizing the importance of boundaries separating Morrowan from Atokan deposits and Desmoinesian from Missourian deposits. The greater significance of the boundaries which delimit Ardian, Oklan, and Kawvian, as compared with boundaries which are recognized within them, is supported by regional stratigraphic relations and paleontological distinctions.
Comparison of classification of Pennsylvanian rocks in the northern midcontinent states, particularly as represented by comprehensive papers published between 1930 and 1945, reveals many divergences, despite growing recognition of the identity of most rock units on opposite sides of state boundaries. Use of a different name for the same rock unit in two adjoining states (as Dennis limestone in Kansas, Hogshooter limestone in Oklahoma) represents lack of uniformity but is not a source of confusion. Use of the same name for different rocks on opposite sides of a State boundary (as Iola limestone and Kansas City group which have been defined in altogether different manner in Kansas and Missouri), is obviously objectionable.
Northern Midcontinent Interstate Conference on Pennsylvanian Classification
A meeting of state geologists representing Iowa, Kansas, Missouri, Nebraska, and Oklahoma, for the purpose of analyzing inter-state divergences in classification and nomenclature of Pennsylvanian deposits in the northern midcontinent area was held in offices of the Kansas Geological Survey at Lawrence on May 5-6, 1947. Those present were as follows: for Iowa, L. M. Cline; for Kansas, R. C. Moore, J. C. Frye, and J. M. Jewett; for Missouri, E. L. Clark, F. C. Greene, and W. V. Searight; for Nebraska, G. E. Condra and E. C. Reed. Wallace Lee, of the United States Geological Survey, attended the sessions as observer. R. H. Dott, State Geologist of Oklahoma, was unable to be present, but on the basis of oral discussion with Moore on May 8 and examination of later written reports has expressed concurrence with qualifications based on differences in the nature of the Pennsylvanian rocks south of the Kansas-Oklahoma boundary.
Discussions at Lawrence extended from 8 a.m. to 6 p.m. on May 5. The following day was devoted to study in the field for the purpose of checking equivalence of Paola-to-Raytown beds in the Kansas City area to the Iola limestone at its type locality and for observations of overlying strata upward to the Plattsburg limestone in the area between Kansas City and Iola. Geologists participating in this field conference were Clark, Greene, Jewett, Moore, and Searight.
The May meeting reached essential accord on all points, subject to acceptance on the part of Missouri of correlations between Kansas City and Iola which had been made by Kansas. The field work on May 6 sufficed to remove doubts of the Missouri geologists on the correctness of identifying the Paola-to-Raytown strata of the Kansas City area with the type Iola limestone, and this permitted agreement of the Missouri Geological Survey to changes in stratigraphic nomenclature which depend on this identification (Moore, 1948).
The substance of all changes adopted by the interstate conference (Fig. 2) which affect classification of the Pennsylvanian rocks in Kansas will be outlined and explained in following parts of this paper.
Figure 2. Main divisions of the Pennsylvanian System recognized by the northern midcontinent interstate conference of geological surveys. Accepted divisions are shown in the columns marked "new"; other columns indicate previously used divisions in the several states. Exception is to be noted, however, in that Oklahoma does not recognize Atokan and uses Skiatook and Ochelata groups as divisions of the Missourian rocks.
I am indebted to associates of the Kansas Geological Survey for aid in preparing this paper, especially John C. Frye, Betty Hagerman, and Marjorie Bradley. Thanks are expressed also to Jack Koenig and Grace Muilenburg for work on maps accompanying the report. The stratigraphic sections and charts have been drawn by me.
Kansas Geological Survey, Geology
Placed on web Jan. 26, 2009; originally published Nov. 1949.
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