U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP I-1970-C U.S. GEOLOGICAL SURVEY MAP SHOWING THE THICKNESS AND CHARACTER OF QUATERNARY SEDIMENTS IN THE GLACIATED UNITED STATES EAST OF THE ROCKY MOUNTAINS NORTHERN AND CENTRAL PLAINS STATES (90° TO 102° WEST LONGITUDE) By David R. Soller INTRODUCTION three-dimensional mapping of these, and other, deposits. Particu larly in populated areas, detailed mapping is vital to the site-specific This map portrays the thickness and character of Quaternary planning and assessment of the effects of human activities at and sediments in the glaciated Northern and Central Plains States beneath the land surface. In contrast, regional maps such as the betwen 90° and 102° West longitude. It is one of a series of four four maps of this series serve to place local, detailed mapping in maps presenting a regional synthesis and interpretation of available context, to permit the extrapolation of data into unmapped areas, geologic data for the continentally glaciated United States east of and to depict large-scale, regional geologic features and patterns the Rocky Mountains (see map, fig. 1}. The numerous references that are beyond the scope of detailed local mapping. This series of (approximately 850} used to compile these maps, the majority of maps is also a regional planning document that can assist in setting the acknowledgments, and a further explanation of the maps are priorities for areas in need of more detailed mapping; subsequent contained in Soller (1992}. Showing both the thickness and detailed mapping should then be incorporated into an updated character of unconsolidated deposits, this map is in essence a regional map. Geologic mapping is an iterative process, and the three-dimensional view of the outermost layer of the Earth. maps of this series should be considered as only an initial regional Because the character of sediments is depicted on this map without view of the glaciated sedimentary framework east of the Rocky implications regarding geologic time or events, the map comple Mountains. ments regional maps that emphasize geologic events, such as the Gladal map of the United States east of the Rocky Mountains (Aint, 1959} and the Quaternary geologic atlas of the United States ACKNOWLEDGMENTS (for example, Uneback and others, 1983}. During map compilation and production, I sought advice from a This map has three data components: the surface distribution of Quaternary sediments, the total thickness of Quaternary sedi number of individuals in different disciplines. These people have ments, and the distribution of significant buried Quaternary units. contributed to the generation of the map, and I am grateful for their The Quaternary sediments. shown in this map series are glacial or help. I particularly thank Byron D. Stone of the U.S. Geological glacially related deposits (including overlying Holocene-sediments}. Survey (USGS} for his suggestions on map concept and project Of limited extent and not shown are areas of Quaternary colluvium scope; John P. Kempton and Richard C. Berg (Illinois State not derived from glacial deposits; as used on these maps, the term Geological Survey} for their encouragement to pursue new tech "Quaternary sediment" does not include this type of colluvium. niques; Kenneth J. Lanfear, Will R. Stettner, and James R. Subsurface information is not available for most of the mapped Estabrook (USGS} for assistance in the technical aspects of map area, and, therefore, the depiction of buried units is uneven. Where digitization and production; and Carl Koteff (USGS} for his efforts buried units are shown, the complex geologic settings in which they in originating this project. My appreciation goes to Albert J. occur are greatly simplified because of the small scale of this map Froelich and James P. Owens (USGS} for reviewing the manu series. script. Population growth and the resulting increase in demand for I also thank the many geologists consulted during this project for agricultural production, construction materials, land development, their willingness to share information and insight, their advice on waste-disposal sites, and ground-water resources have created a mapping interpretations, and their comments during map review. growing need for three-dimensional geologic maps that can be Their names are listed in Soller (1992}. directly applied to hydrologic, environmental, and land-use prob lems. Such maps depict the texture of surface and subsurface DIGITAL MAP PRODUCTION AND THE BASE MAP geologic materials, commonly to a specified depth or geologic contact. The glaciated region of the United States depicted in this The maps of this series were produced by newly developed map series has a particular need for three-dimensional geologic digital cartographic techniques (Soller and others, 1990}. Although mapping. Approximately 40 percent of the U.S. population resides a discussion of these techniques is not within the scope of this within the mapped area, which is less than one-quarter the size of report, a few comments on digital map production and the base the conterminous United States. The region also contains a major map are appropriate, because they affected map content. The portion of the Nation's agricultural and industrial capacity. maps of this series span four sheets (this map sheet, and Soller This map series is a regional overview of the three-dimensional (1993, 1994, and in press a}). Each sheet consists of a hand distribution of sediments for a large area and is intended to· mosaicked group of 4° x 6° quadrangles from the International supplement the more detailed work on which it is based. I hope Map of the World and Army Map Service 1:1 ,000,000-scale maps. that this series of maps will generate interest in more detailed Because these map sheets cover as much as 12° of latitude and 1 longitude and because each quadrangle has unique projection to extent of coverage, level of detail, and suitability of the source parameters, the mosaic is not precise. Between certain quadran maps for reinterpretation. gles, gaps exist in the base map. In order to preserve the In general, surficial map units are defined by terrain, map scale, registration of the geologic information to the base map without and mapping approach (for example, stratigraphic, geomorphic, or sacrificing the spatial integrity of the digital data, entire map sheets sediment type). As a result, map units may not correlate with units were not digitized. Rather, the four layers of geologic information on maps in nearby areas. For example, a map that emphasizes geologic events such as ice stillstand and moraine-building, or shown on the map (that is, character of sediments exposed at the inundation by glacial lakes, may not correlate with an adjacent map surface, thickness of Quaternary sediments, buried units and showing kinds of surficial sediments; where the event-oriented map surface veneer units, and miscellaneous point and line information) may show a moraine composed largely of till, the sediments were digitized separately for each 4° x 6° quadrangle and recom oriented map shows the actual distribution of sediment types bined onto the base map. without delineating the moraine. Although surficial geologic maps of one kind or another are available for much of the region, soil MAP UNITS survey maps were used to assist in mapping areas where geologic The map units depict the distribution of sediment textures at the data were sparse. In many areas, soil surveys were useful, but in land surface, the total thickness of Quaternary sediments, and some places, for example on till plains that were inundated by selected subsurface data. Different colors are used to depict glacial lakes or where eolian sand or silt occurs as a veneer over character of sediment at the land surface. Variations in color glacial deposits, the soil surveys' usefulness is limited. In rare intensities depict thickness of Quaternary sediments, and over instances, only topographic map coverage was available, and it printed patterns depict selected subsurface information. On these was used to interpolate between mapped areas. maps, Quaternary sediments include glacial and glacially related To achieve consistency in mapping across such a large area, and deposits, a minor amount of Pleistocene nonglacial sediments to unify the wide spectrum of mapping styles and glacial geologic within the glaciated area, and Holocene sediments that may or settings, a simple uniform classification of deposits was devised. may not overlie glacial deposits. The term "glacially related" refers This classification is based on the overall character of the sediment; here, the term "character" includes consideration of a sediment's to nonglacial sediments that owe their existence to the activity of lithology, grain size, sorting, stratification, and depositional envi glacial ice; for example, the lacustrine sediments deposited in ronment, and defines the texture of the sediment as well as its outwash-dammed lakes in northern Kentucky and adjacent States origin. In all four maps, definitions of sediment character .a re by nonglacial streams. Areas of Quaternary colluvium not derived necessarily broader than would be required for any local area, so directly from glacial deposits are small and are not shown. that the simple, uniform system would be applicable across the The density and detail of source information varied greatly over entire area, from Maine to Montana. . the region; detailed, sediment-based three-dimensional maps were This classificatiQJil is limited to the following sediment types: till published for some areas, whereas glacial geologic information was (poorly sorted and poorly stratified sediment), coarse-grained lacking for other areas. An assessment of data quality and reliability stratified sediment, fine-grained stratified sediment, organic-rich for both surficial and thickness information is shown in figures 2 sediment (peat, for example), and windblown sediment (mostly and 3, respectively (see map), which are discussed in the "Surficial loess) where it occurs at the surface. Loess is largely silt; eolian mapping" and "Thickness mapping" sections below. sand is included in the category of coarse-grained stratified sedi A three-dimensional map could show the nature and extent of ment and is mapped as a veneer. These deposits are each every subsurface unit; however, subsurface data available for the discussed below. mapped area were sparse, and only well-delineated buried units could be shown. Although subsurface stratigraphy is not well Till known, the total thickness of these glacial (and postglacial) deposits Till, the most widespread unit on these maps, consists of material can be confidently estimated in most places. The Quaternary deposited in contact with glacial ice; in the other units, sediment sediments map, therefore, through the thickness information, was sorted by water or wind prior to deposition. Till is a poorly shows the generalized framework of the glacial deposits. An sorted and generally unstratified deposit composed of particles understanding of three-dimensional variations in sediment texture ranging in size from clay to large boulders (see map, fig. 4). The within the glacial deposits must come from future three relative proportions of these size fractions can vary greatly due to dimensional studies in greater detail. several factors, resulting in a textural range from dense and In the Atlantic Ocean, the Great Lakes, and in some other large compact clayey till with few grains larger than sand size, to loose, lakes, the underlying geology is shown only in places where studies sandy till with abundant boulders and only small amounts of the have been made. In these cases, water areas where no geologic finer size fractions. The dominant grain size and the distribution of data are shown are tinted gray. In most lakes, however, no studies particle sizes are generally referred to as the texture of the till. A of the underlying geology have been undertaken. To simplify map discussion of the relation between till texture, lithology of the preparation and digitizing, the author used a somewhat arbitrary underlying bedrock, and pattern of ice lobation is provided in division for these lakes: for relatively small lakes, geologic data Soller (1992). were extrapolated from surrounding land, while for larger lakes no attempt at extrapolation was made, and they are tinted gray. Stratified sediment Sediment released from melting glaciers is generally sorted by SURFICIAL MAPPING running water and is found as a stratified deposit in a variety of The quality of the surficial map data and extent of map coverage settings, including glaciolacustrine, glaciofluvial, and outwash plain. varied widely. A relative, and subjective, measure of the quality of These deposits are subdivided by grain size (fig. 4). However, as the source maps and the resulting reliability of the surficial map shown in figure 4 and discussed below, coarse-grained and data are shown in figure 2. In this context, the term "quality" refers fine-grained stratified deposits have overlapping textural ranges. 2 Coarse-grained stratified sediment glacial deposits where postglacial drainage is poor. In most areas, it These deposits generally consist of layered sand and gravel, with occurs in relatively small patches, but in northern Minnesota, peat less common silt and clay beds, deposited in fluvial, glaciofluvial, is extensive and covers a poorly drained part of the glacial Lake deltaic, and outwash-plain settings. Holocene alluvium has also Agassiz basin. This unit is generally less than 20ft thick; therefore, been included in this unit; in places it is silty or clayey, and it may where the total thickness of Quaternary sediments exceeds the overlie glacial sand and gravel. In many valleys, thick glacial lowest thickness value mapped (50ft), the unit is inferred to overlie meltwater sediments underlie thin Holocene alluvium. During older Quaternary sediment. In such areas, organic-rich sediment is deposition of this unit, changes in flow regime and sediment supply depicted as a veneer, and the unit known or inferred to lie beneath it is also mapped. Methods for portraying the veneer and the were common, and sediment texture varies correspondingly. Thus, underlying unit on the map are discussed in the "Subsurface some interbedded fine-grained sediment is included in this unit (see fig. 4). Eolian sand, which has.a patchier and more limited mapping" section below and in the Description of Map Units. distribution than loess, is likewise shown only as a veneer (of coarse-grained stratified sediment). Loess In some areas, outwash in major valleys dammed tributary Loess is windblown silt and lesser amounts of sand; it covers stream valleys, creating lakes behind the outwash. Late Wisconsi many upland areas in the central United States (Thorp and Smith, nan lake sediments in tributaries in southern Illinois, southern 1952). Across the area covered by these maps, loess thicknesses Indiana, and northern Kentucky formed in this way. In many range from 0 to more than 100 ft, but loess is commonly less than places, these lakes occurred outside the limit of glaciation and thus 8ft thick (Thorp and Smith, 1952) and in many places has been contain sediments of nonglacial or periglacial origin. Because these mixed into the underlying deposit by farm implements or natural lake sediments are related to glacial action, they are included on processes. Although it is a widespread surface unit, loess is shown the map. Some of these lake sediments and some fluvial deposits only where it exceeds 20 ft in thickness and then only as a veneer (for example, those along the western margin of the mapped area to avoid undue emphasis (see "Subsurface mapping" discussion in Nebraska and in the Mississippi River valley in Missouri) are so below and example in "Stack-unit mapping" section of the far beyond the limit of glaciation that their relation to glacial Description of Map Units). Loess is generally not shown over processes is highly speculative. stratified deposits in stream valleys because it is assumed that late In Nebraska, near the western limit of glaciation, fluvial sand and glacial and Holocene erosion has largely removed the loess or gravel of Pleistocene age derived from western sources are inter incorporated it into fluvial sediment (that is, into the coarse-grained bedded with eastern-source glacial outwash. Of necessity, these stratified unit). However, near the glacial border in Nebraska, thick western-source sediments have been included in this unit. Some of loess is mapped over outwash deposits. the geologic section is interbedded loess, or loess reworked and deposited as a silty fluvial unit; this loess is especially common in Patchy Quaternary sediment the upper part of the section but could not be shown separately at this map scale. Quaternary sediment does not blanket the surface in some parts of the glaciated area. There, patchy Quaternary sediment may Fine-grained stratified sediment occur with exposures of bedrock, of residuum, or of alluvium or These deposits generally are clay, silt, and very fine sand but colluvium not derived from glacial deposits. The proportion of include lesser amounts of coarser material (fig. 4), commonly as nonglacial to glacial material in these areas ranges from numerous interbeds. Fine-grained stratified sediments were deposited in quiet isolated exposures of bedrock in an area of thin till, to patchy, water, mostly in proglaciallakes. In some parts of the Great Lakes isolated exposures of till or stratified deposits on a bedrock and the Atlantic offshore area, thick accumulations of Holocene landscape that has preserved little evidence of glaciation. In many mud overlie fine-grained stratified glacial-lake sediments; these areas, Quaternary sediment is absent or sparse both near the limit muds are included in this map unit. This unit also includes the finer of glaciation and in mountainous or dissected areas within the grained lake sediments that occur in tributaries dammed by glaciated region. Extensive areas of bedrock occur mostly in outwash in major valleys outside the limit of glaciation. These upland areas where Quaternary sediments are dominantly till. deposits, as mentioned previously, are inferred to be glacially Therefore, the map color is the same for patchy sediment as for till, related, but this inference is in some places highly speculative. and a pattern is used to distinguish it from areas of continuous till On old lake plains, particularly around the Great Lakes, clayey cover. In one broad area in the St. Lawrence lowland in northern till commonly has been winnowed by lake waters or has incorpo most New York near Lake Ontario, the patchy sediment is not till rated an earlier lake deposit. These tills may superficially resemble but is mostly fine-grained stratified deposits. fine- or coarse-grained stratified lake sediments, but they retain essential characteristics of till and are mapped as such. On previous maps of this region (for example, Aint, 1959), these lake plains THICKNESS MAPPING were largely mapped as lake sediment. In Montana and North Dakota, previous maps (Colton and others, 1961, 1963) showed The quality and distribution of thickness data vary greatly lake deposits in areas inundated by proglaciallakes; these deposits, because the data base ranges from detailed statewide compilations however, are quite sparse and are not shown on the maps of this to sparse and poorly distributed control by well logs. A relative, and series. subjective, measure of the quality of the source maps and the resulting reliability of the thickness data are shown in figure 3. In Organic-rich sediment this context, the term "quality" refers to extent of coverage and Organic:-rich sediment, consisting mostly of peat, swamp depos level of detail. For 11 States, this map series provides the first its, and marsh deposits, occurs on the youngest (late Wisconsinan) statewide thickness map of Quaternary deposits; it is also the first 3 drift-thickness map for the areas under water. For nearly all of the ations occur both vertically and laterally over short distances. In remaining States, new or unpublished thickness data supple Illinois (Berg and others, 1984 [map scale 1:500,000], and Berg mented the existing maps. and Kempton, 1988 [map scale 1:250,000]) and in Connecticut The surfiCial character of the sediments was compiled and then (Stone and others, 1992 [map scale 1:125,000]}, subsurface data used, with topography, as a guide for mapping sediment thickness are presented by map units each representing a vertical "stack" of in places of limited data. This procedure improved the continuity lithologic units (see Kempton, 1981, for a discussion of the and reliability of thickness contours in many areas, for two reasons. stack-unit concept}. These maps are complex and portray the Rrst, the contact between surficial lithologies may mark a large subsurface data effectively. However, their methods of showing change in overall thickness of deposits. For example, on the relatively detailed subsurface data are not feasible on the four maps Appalachian Plateau of west-central New York, uplands covered of this series; data density and reliability are highly uneven from by thin deposits of till are dissected by deep, narrow valleys State to State, and in certain areas the deposits are too thick and containing sequences of stratified, water-lain sediment commonly the stratigraphy too complex to be portrayed by their methods. more than 200 ft thick. At the map scale of 1:1,000,000, the In general, the subsurface is not shown on the four maps of this contact between till and stratified sediment closely approximates series because data are insufficient. In the areas where the the valley wall; even where thickness data are sparse this contact subsurface is well known, the vertical succession of geologic units serves as the guide to constrain the thickness contours to the is depicted on the map in a generalized fashion, as a two-unit stack stratified sediment areas within the valley. Without the surficial consisting of either the surficial unit and a well-mapped buried unit geology as a constraint, the limited well-log data would be of use of some significance (for example, an aquifer) at some unspecified only as point data; however, where surficial geology and topogra depth, or a discontinuous surface veneer of sediment and the phy are considered, these limited data are used most effectively to underlying unit. The stack units are shown by colors and patterns project thickness contours into areas with little or no well-log data. on the maps, to convey the existence and general configuration of Second, in many areas, topographic relief is sufficient to signifi cantly affect the thickness of the underlying sediments. Some regional, large-scale geologic features. These stack units include, compilations used in the preparation of these maps are so gener but are not limited to, the following deposits: stratified sediments alized that the thickness contours are not constrained by relief of overlying till in a glacial lake basin; sand and gravel aquifers buried the land surface. Where thick deposits in a buried valley are deeply beneath till; and areas of peat or of eolian sediments (loess or dissected by crosscutting modem drainage, the thickness contours eolian sand} capping older Quaternary sediments. These buried or should not cross the low areas of the dissected terrain. On the four veneer units are commonly widespread or thick, and may be maps of this series, where modem stream valleys overlie buried of economic as well as geologic significance (for example, as valleys, the thickness contours that depict thick sediments in the aquifers). buried valleys are generally constrained by th~ limits of the modem As shown in the examples given in the "Stack-unit mapping" valley, especially where bedrock is exposed along valley walls. section of the Description of Map Units, these two-unit stacks In a few areas, because of lack of available data, the glacial should not be interpreted to portray the actual vertical succession sediments cannot be differentiated from underlying deposits. of units. Where a buried, coarse-grained stratified unit is depicted, Beneath the thick drift of Michigan's southern peninsula, red beds it may occur at the base of section beneath till, or beneath till that of possible Jurassic age are patchily distributed (Schaffer, 1969; contains numerous interbeds of stratified deposits and peat, or at Rhoads and others, 1985}. The distribution of these red beds is some other position within the section, perhaps bounded above uncertain, and they are difficult to recognize on well logs; therefore, and below by till. However, the stack does indicate the occurrence some minor part of the sediment thickness in Michigan as shown of a well-known, significant buried unit. AlsQ, where a veneer of on the map (Soller, in press a} may be the red beds. loess is mapped over till, it is not implied that the entire section Elliptical landforms, shaped and oriented by overriding ice, are beneath the loess is till. Stratified deposits may be buried beneath common in some areas. They are generally composed of dense, or interbedded with till, as is certainly possible in areas where stack compact till, but may be rock-cored or entirely rock. The compo units are not shown. Unmapped, speculative variations in sediment sition of these streamlined landforms can be determined by character at depth pre not shown here. A comprehensive map of augering; however, since drill data are uncommon, most maps the subsurface, based in part on extrapolation of available data, is (including these} treat all oriented, streamlined landforms as a the proper role of detailed, three-dimensional mapping, not of a group. Drumlins are streamlined hills that are generally composed regional map such as this. of till, and in areas of thin till these features are relatively thick Through the use of colors and patterns, the stack units empha accumulations of till. In New England, where till is typically less size either the surficial unit or the buried unit, depending in part on than 15 ft thick on the uplands, till beneath drumlins commonly is their relative thicknesses and in part on knowledge of the subsur more than 40 ft thick. Although less thick than the lowest contour face. For example, where a patchy veneer of peat or of fine value, and of small size, drumlins are shown on the maps of this grained stratified lake sediment overlies a thick sequence capped series by symbols. by till, the till is shown as the solid map color, and the thin overlying Nearly all thickness and topographic data used to compile these unit appears as a pattern of diagonal stripes whose color reflects maps were reported in U.S. customary units (feet}. For simplicity that ·unit's lithology. Where the geometry of a buried unit (for and accuracy during map compilation, this system was retained. A example, stratified sand and gravel filling a buried valley) is fairly metric conversion table is included to assist those readers desiring well defined, the surficial unit is shown in a solid color, and the to work with metric units. buried unit is represented by a dot pattern of the appropriate color. To illustrate the variations in subsurface lithologies that may SUBSURFACE MAPPING actually be encountered at depth, lithologic logs from different Characterizing subsurface variations in lithology is exceedingly geologic settings (for example, buried valleys and upland areas) are difficult in nonmarine Quaternary sediment, because textural vari- shown in figure 5 below. · 4 SUMMARY --1963, Preliminary glacial map of North Dakota: U.S. Geo logical Survey Miscellaneous Geologic Investigations Map The four maps in this series can be placed in perspective by 1-331, scale 1:500,000. emphasizing the following points: Aint, R.F. (committee chairman), 1959, Glacial map of the United 1. The mapping emphasis differs from most published State and States east of the Rocky Mountains: Boulder, Colo., Geolog regional surficial geologic maps, which use stratigraphic or geomor ical Society of America, scale 1:1,750,000. phic map units and focus on the chronology of geologic events Kempton, J.P., 1981, Three-dimensional geologic mapping for such as ice advances or retreats, or the history of glacial lakes. The environmental studies in Illinois: Illinois State Geological actual character of the sediments is necessarily given a subordinate, Survey, Environmental Geology Note 100, 43 p. albeit significant role on those maps. In contrast, these maps show Lineback, J.A., Bleuer, N.K., Mickelson, D.M., Farrand, W.R., and the character of surficial sediments without regard to age of the Goldthwait, R.P., 1983, Quaternary geologic map of the deposits. Because of this fundamental difference, the distribution of Chicago 4° x 6° quadrangle, United States, in Richmond, sediments on event-oriented maps may not agree with these maps. G.M., and Fullerton, D.S., eds., Quaternary geologic atlas of For example, in many glaciated areas inundated by proglacial the United States: U.S. Geological Survey Miscellaneous lakes, the surficial sediment is commonly till, somewhat altered Investigations Series Map 1-1420 (NK-16), scale where reworked by the lake water. On event-oriented maps, 1:1,000,000. however, because of the glacial geologic history, lacustrine clay, Rhoads, B.L., Rieck, R.L., and Winters, H.A., 1985, Effects of silt, and sand are commonly mapped (inferentially) throughout a thick drift on Quaternary landscapes in central Michigan: lake plain, although these deposits may be areally subordinate to Michigan Academician, v. 17, p. 301-315. Schaffer, B.L., 1969, Palynology of the Michigan "Red Beds": East till. Additionally, while the four maps of this series differentiate Lansing, Mich., Michigan State University, Ph.D. dissertation, between areas where Quaternary sediments have been preserved 250p. and where they were eroded or never deposited, maps emphasiz Soller, D.R., 1992, Text and references to accompany "Map ing stratigraphy or geomorphology have usually included extensive showing the thickness and character of Quaternary sediments areas of bedrock or nonglacial sediment in the glacial map units in the glaciated United States east of the Rocky Mountains": (for example, Flint, 1959; Colton and others, 1961, 1963). U.S. Geological Survey Bulletin 1921, 54 p. 2. These maps depict the surface distribution of sediments and --1993, Map showing the thickness and character of Quater the total thickness of the Quaternary deposits; the continuation of nary sediments in the glaciated United States east of the the surficial unit down to the pre-Quaternary surface ("bedrock") Rocky Mountains-Northeastern States, the Great Lakes, and cannot necessarily be inferred, although this may commonly be the parts of southern Ontario and the Atlantic offshore area (east case especially in areas where the Quaternary sediment is thin. of 80°31' West longitude): U.S. Geological Survey Miscella 3. These maps are a regional first approximation of the three neous Investigations Series Map 1-1970-A, scale dimensional distribution of sediments over a very large area. They 1:1,000,000. are intended to encourage additional research and detailed map --1994, Map showing the thickness and character of Quater ping. They are also intended to supplement, not supersede, the nary sediments in the glaciated United States east of the local, detailed studies from which they were compiled, and should Rocky Mountains-Northern Plains States (west of 102° not be used to infer specific details concerning the local geologic West longitude): U.S. Geological Survey Miscellaneous Inves tigations Series Map 1-1970-D, scale 1:1,000,000. framework; they are not site-specific maps. Complementing --in press a, Map showing the thickness and character of detailed mapping, regional maps such as these place local, detailed Quaternary -sediments in the glaciated United States east of mapping in a regional context, permit the extrapolation of data into the Rocky Mountains-Northern Great Lakes States and unmapped areas, and depict large-scale, regional geologic features central Mississippi Valley States, the Great Lakes, and south that are beyond the scope of detailed local mapping. A regional em Ontario (80°31' to 93° West longitude): U.S. Geological map in many cases will point out a problem or relation that is not Survey Miscellaneous Investigations Series Map 1-1970-B, apparent on a detailed map, which will allow information from the scale 1:1,000,000. detailed map to be reinterpreted. Soller, D.R., Stettner, W.R., Lanfear, K.J., and Aitken, D.S., 1990, A user's manual for a method of map scanning and digital REFERENCES CITED editing for thematic map production and data-base construc tion: U.S. Geological Survey Circular 1054, 38 p. These references ar~ cited in the text. References pertaining to Stone, J.R., London, E.H., and Langer, W.H., 1979, Map showing data gathering for the map compilation are listed in Soller (1992). textures of unconsolidated materials, Connecticut Valley urban area, central New England: U.S. Geological Survey Berg, R.C., and Kempton, J.P., 1988, Stack-unit mapping of Miscellaneous Investigations Series Map 1-1074--B, scale geologic materials in Illinois to a depth of 15 meters: Illinois 1:125,000. State Geological Survey Circular 542, 23 p., map scale Stone, J.R., Schafer, J.P., London, E.H., and Thompson, W.B., 1:250,000. 1992, Surficial materials map of Connecticut: Reston, Va., Berg, R.C., Kempton, J.P., and Cartwright, Keros, 1984, Potential U.S. Geological Survey special map, scale 1:125,000. for contamination of shallow aquifers in Illinois: Illinois State Thorp, James, and Smith, H.T.U. (co-chairmen, National Geological Survey Circular 532, 30 p., map scale 1:500,000. Research Council Committee for the Study of Eolian Depos Colton, R.B., Lemke, R.W., and Lindvall, R.M., 1961, Glacial map its, Division of Geology and Geography), 1952, Pleistocene of Montana east of the Rocky Mountains: U.S. Geological eolian deposits of the United States, Alaska, and parts of Survey Miscellaneous Geologic Investigations Map 1-327, Canada: Boulder, Colo., Geological Society of America scale 1:500,000. [map], scale 1:2,500,000. 5 IA-1 IA-2 IA-3 IA-4 IA-5 IA-6 KS-1 KS-2 MN-1 M0-1 M0-2 M0-3 M0-4 0 50 100 100 100 100 100 100 100 100 100 100 100 200 200 200 200 200 200 300 300 300 300 400 400 EXPLANATION OF PAITERNS D ~~lu~l Till Silt. and clay - I: ..... ·:.-_:: I ~ ..1 Sand and gravel 1~~? Silt and clay with some coarser sediment; D . Gravel, sand, silt, and unit possibly is till, clay (sorting or bedding although log is not not reported on log) specific ~. Silt (loess) D Bedrock ' Depth scales show feet below ground surface Figure 5. -Selected lithologic logs illustrating subsurface lithologic variations in different geologic settings, including buried valleys, river valleys, and upland areas. Locations are shown on map. Logs were selected to alert the map user to the potential vertical lithologic variatiol')s in different settings, and to show the subsurface in certain areas where stack units are mapped. Similar lithologic variations in similar geologic settings are not implied; therefore, extrapolation of log data should be avoided. Depth scales show feet below ground surface. 6 DESCRIPTION REFERENCES Iowa Emmett, L.F., and Jeffery, H.G., 1968, Reconnaissance of the IA-1-Loess over thick section of multiple tills on uplands ground-water resources of the Missouri River alluvium between Cedar and Iowa Rivers, southwest of Waterloo (Hall between St. Charles and Jefferson City, Missouri: U.S. Geo berg, 1980, Fourmile Creek composite section) logical Survey, Hydrologic Investigations Atlas HA-315. IA-2-Sand overlying multiple tills, near Iowa River northwest of ---1970, Reconnaissance of the ground-water resources of Iowa Falls (Iowa Geological Survey, unpublished log, Dows the Missouri River alluvium between Miami and Kansas City, Quarry site) Missouri: U.S. Geological Survey, Hydrologic Investigations IA-3-Thick section of multiple tills on uplands in southwestern Atlas HA-344. Iowa, south of Massena (Iowa Geological Survey, unpublished Gann, E.E., Harvey, E.J., Jeffery, H.G., and Fuller, D.L., 1971, log, Massena corehole site) Water resources of northeastern Missouri: U.S. Geological IA-4-Thick section of multiple tills on uplands in southwestern Survey, Hydrologic Investigations Atlas HA-372. Iowa near Missouri border, east of Mount Ayr (Iowa Geological Hallberg, G.R., 1980, Pleistocene stratigraphy in east-central Survey, unpublished log, Mount Ayr corehole site) Iowa: Iowa Geological Survey, Technical Information Series IA-5-Thick loess over till and stratified sediment, east of the no. 10, 168 p. Missouri River valley near Pisgah (between Sioux City and Schultz, C.B., and Smith, H.T.U., eds., 1965, Central Great Council Bluffs) (Iowa Geological Survey, unpublished log, bor Plains: Guidebook, INQUA field conference D, 7th Con ing no. WC-24) gress, International Association for Quaternary Research, IA-6-Thick section of alternating till and stratified sediment in 128 p. northwestern Iowa, northeast of Ocheyedan (Iowa Geological Walters, K.L., 1954, Geology and ground-water resources of Survey, unpublished log, test boring no. D--13) Marshall County, Kansas: Kansas State Geological Survey, Bulletin 106, 116 p. Kansas Ward, J.R., 1973, Geohydrology of Atchison County, northeast KS-1-Thick till filling buried valley in northeastern Kansas, ern Kansas: U.S. Geological Survey, Hydrologic Investiga south of Vermillion (Walters, 1954, test hole no. 4-10-25dd) tions Atlas HA-46 7. KS-2-Till overlying stratified sediment in buried valley on uplands in northeastern Kansas, east of Delaware River and south of Muscotah (Ward, 197 3, test hole no. 6-17E-14ccb) Minnesota MN-1-Till and stratified sediment on upland in central Minne sota, south of Eagle Bend (Minnesota Geological Survey, unpublished test hole no. CC-19) Missouri M0-1-Alluvium in Missouri River valley, east of St. Charles (Emmett and Jeffery, 1968, cross section A-A') M0-2-Alluvium in Mississippi River valley, north of St. Charles (Gann and others, 1971, cross section G-G') M0-3-Alluvium in Missouri River valley, in west-central Mis souri south of Wakenda (Emmett and Jeffery, 1970, cross sec tion A-A') M0-4-Till overlying sand in buried valley south of Missouri River valley, in west-central Missouri near Malta Bend (Emmett and Jeffery, 197 0, cross section A-A') Figure 5.-Continued 7 00 § 8 8 8w 8N 8 Cl z ~~~~~~~~~~~~~~~~~~: ~~~~~~~~~~~~~~~~~~- ~ ,,~~~~ ~~~~~~ ~~~~~~ ~~ ~ ~ 8 z ~ DD r n . . ~ 8 g z § ::;:1-00C1) ~ g_ ~ <: c.. 0 ~Cil..m.. [ l(1 ) 'g0 _0a ~ 8 Cl ro:::1c.. tQ z ~ 0c ,.0C O~! a. &D1 ~ ~ ::::1 '"" ::;:' (I) - 0'"~ ~ ~~::::1 8 8 8 ~ ~c.. ~ ~ ~a tQ .. · .... -: .. _·::-: ..- r:r· ...· ..\ . :_: ...1 z r: ..· .. ··:"->: :•, ..- ... ;::,..-·:·. ? ~ f 0.,. , . . . . . . . t7l D ?1 I 3 - ~.i 8 ~ 8 8 () ' ~ Cl c:0:rr::::o::s1 t . [sg(I::)_ ca~.. g~ -~:=:;=:' C/) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mz.!.. 0.. 0 (~") %c.. .mse.. 8 8 8 CIl ?, .: ~ 1. .. ·II : I : I I : I : I v-: .- : · ·· .. "I:- 11 : I : I :r .. :. ·. :. .... ·l ~ I~ 1~ ~ ~ li ! ! i ! i ! ! z m ~ I·'J'I'I'I'I'I· 'I' 'II ···- .- - 1•11•1•111 NI 8 8 8 8 I I 'I I. ,11 . .1 z m 6J 8CC I 8.... . 8 8 8 8 8 8 C/) ~ -...-...-... , ·I..-,.... ... I ·4 8 I I ~ :!: fJ ~~ ~~ ~~ DESCRIPTION REFERENCES Arndt, B.M., 1975, Geology of Cavalier and Pembina Counties: Nebraska North Dakota Geological Survey, Bulletin 62, Part 1, 68 p. NE-1-Thick loess over till and stratified sediment, on the Bluemle, J.P., 1981, Geology of Sheridan County, North uplands between the Platte and Elkhorn Rivers in eastern Dakota: North Dakota Geological Survey, Bulletin 75, Part Nebraska, southeast of Norfolk (Conservation and Survey Divi 1, 59 p. sion, 1953, hole no. A21-3-17ad) Carlson, C.G., and Freers, T.F., 1975, Geology of Benson and NE-2-Thick loess and till overlying stratified sediment, on the Pierce Counties, North Dakota: North Dakota Geological uplands between the Platte and Elkhorn Rivers in eastern Survey, Bulletin 59, Part 1, 32 p. Nebraska, southeast of Norfolk (Schultz and Smith, 1965, fig Keech, C.F., and Dreeszen, V.H., 1968, Geology and ground ure 3-16, hole no. CSL-SW-SE-sec.29-22N-4E). water resources of Fillmore County, Nebraska: U.S. Geolog Part of the stratified sediment may be from a western, non ical Survey, Water-Supply Paper 1839-L, 27 p. continentally glaciated source (Vince Dreeszen, Nebraska Geo Klausing, R.L., 1968, Geology and ground-water resources of logical Survey, personal commun., 1986) Cass County, North Dakota: North Dakota Geological Sur NE-3-Extensive outwash deposits along the glacial margin, in vey, Bulletin 47, Part 1, 39 p. southeastern Nebraska south of Exeter (Keech and Dreeszen, Mickelson, D.M., Clayton, Lee, Baker, R.W., Mode, W.N., and 1968, hole no. 7-1-3aa) Schneider, A. F., 1984, Pleistocene stratigraphic units of North Dakota Wisconsin: Wisconsin Geological and Natural History Sur ND-1-Alternating till and sand, beneath stagnation moraine vey, Miscellaneous Paper 84-1, 97 p. and over a buried valley, in central North Dakota north of Den Nebraska University, Conservation and Survey Division, 1953, hoff (Bluemle, 1981, hole no. 5347) Logs of test holes, Stanton County, Nebraska: 25 p. ND-2-Alternating till and stratified sediment in a buried valley, Schultz, C.B., and Smith, H.T.U., eds., 1965, Central Great in central North Dakota west of Sheyenne River (Carlson and Plains: Guidebook, INQUA field conference D, 7th Con Freers, 1975, hole no. 5311) gress, International Association for Quaternary Research, ND-3-Generally fine-grained stratified sediment and till, on the 128 p. glacial Lake Agassiz plain in northeastern North Dakota, north of St. Thomas (Arndt, 1975, hole no. 5940} ND-4-Generally fine-grained stratified sediment and till, near western margin of glacial Lake Agassiz in northeastern North Dakota (Arndt, 1975, hole no. 4220) ND-5-Coarse-and fine-grained stratified sediment of Sheyenne delta built into glacial Lake Agassiz and overlying till, in south eastern North Dakota south of Leonard '(Klausing, 1968, hole no. 137-52-31bbb} South Dakota SD-1-Thick section of alternating tills and coarse-grained strati fied sediment in the interlobate Prairie Coteau region, in east ern South Dakota west of Tunerville (South Dakota Geological Survey, unpublished log, test hole no. DR-7308} Wisconsin WI-1-Locally thick occurrence of alternating till and stratified sediment in an otherwise thinly mantled area near Lake Supe rior, on the Bad River north of Mellen; surficial sand is not widespread enough to be mapped (Mickelson and others, 1984, type section of Copper Falls Formation} Figure 5.-Continued oU.S. GOVERNMENT PRINTING OFFICE:1998-673-441/23002 9