Prepared and Published with the Support of COUNTY ATLAS SERIES THE CROW WING COUNTY BOARD OF COMMISSIONERS AND ATLAS C-16, PART A MINNESOTA GEOLOGICAL SURVEY THE MINNESOTA DEPARTMENT OF NATURAL RESOURCES, DIVISION OF WATERS Plate 3—Surficial Geology Harvey Thorleifson, Director SURFICIAL GEOLOGY R. 29 W. 94°15' R. 28 W. R. 27 W. 94°00' R. 26 W. R. 25 W. CASS COUNTY Lizzie Lake 5 Jail Island pe 40 Lake Lake 435 bis 5 5 6 Goose bc pe 1 6 1 5 Allen 40 1 By bis 40 6 Wolf Lake Little Pine 1 40 1 6 bt Lake Papoose 405 pe 435 pe Lake Lake bt 390 Lake 390 bc Stewart bc 405 bt Lake pe 390 390Roosevelt KNAEBLE bc Clough bt 435 0 pe Alan R. Knaeble, Gary N. Meyer, and Howard C. Hobbs 0 pe al Lake Lake 39 405 42 bt 5 405

435 AITKIN COUNTY Squaw 40 pe Mitchell 390 bo 420 0 Lake 2004 Lake 39 Blue ml bo Kego Lake 420 bt Lake bo Anna 6 bt ml Lake 390 5 GAIL LAKE 390 bt TIMOTHY 40 pe T. 138 N. FIFTY LAKES EMILY pe LITTLE PINE bc T. 138 N. CORRELATION OF MAP UNITS pe pe 390 pe pe 405 Duck Eagle Lake MEYER bo bt Lake Ruth West Lake mc 46°45' Eolian Fluvial Glacial Lacustrine Paludal Anthropic 46°45' bt Fox Butterfield bt bc bc bis0 ml Lake 39 Lake 405 Buchite bis pe bo 0 Lows bt Lake 39 dl bo mc Lake Lake Mary al 390 pe 405 pe bis Brook ld Holocene bt Sand 390 bc pe 390 Lake 0 39 lt 31 pe pe ml bc 36 Trout Lake 390 36 ml 36 31 31 390 Lake Emily pe mc agl INDEX TO MAPPING 405 Big Trout bc 36 31 ut atw pe Pickerel 36 Grass Dahler mi mt Bass atl als QUATERNARY Lake Daggett Lake The index above shows the portions of Crow Wing 390 Lake Lake 390 Lake 0 390 bo 390 mbo Late Ox 5 County mapped by Knaeble and Meyer. The two dashed 39 375 40 Island pe mo mi mc mt ml Wisconsinan bo pe 6 Lake Lake 7.5-minute quadrangles (Gull Lake and Brainerd) were 1 6 1 390 1 Pleistocene 390 6 pe 1 6 1 bgl originally mapped by Hobbs (2001a, b) with subsequent pe mt bo bis bc bt btd bl 375 bc Little mc bt modifications by Knaeble. 390 mt ml bc 405 Pine Lake 375 mbo 375 405 390 ml pwt Pre-Late Upper Wisconsinan 375 bt Whitefish 420 pe Lower 405 bt al Lake Goodrich Lake 405 Whitefish Rush pe Island pe 390 Lake bc Lake mc Lake 5 mc 375 ROSS37 LAKE 375 ml mbo Mixed outwash—Sand, gravelly sand, and gravel; cobbly in places, especially bo mbo375 INTRODUCTION MAP SYMBOLS bo near former ice margins. May include ponded fine-grained sediment along 375 420 mt 0 The surficial geologic map shows the materials expected to be encountered at the land Geologic contact—Approximately located. 5 375 39 former ice margins. Includes loamy, poorly sorted intervals in places. 37 CROSS LAKE Dolney ml T. 137 N. pe FAIRFIELD T. 137 N. surface beneath the topsoil in Crow Wing County. The surface materials can be simplified The surface of the deposits has collapsed in places from ice-block melt- Eolian sand—Pattern indicates windblown sand as thick as 10 feet (3 meters) on top bc Lake mc 375 into three types: till (unsorted sediment [diamicton] deposited by glacial ice), sand and JENKINS Lower IDEAL bo out. Mantled in places by 3 feet (1 meter) or more of sandy loam- to of other mapped sediments. In a few places west and south of Brainerd Cross 375 Ross pe Hay Lake Roger pe gravel, and lacustrine sand (Fig. 1). Unit contact lines, descriptions, and map symbols loamy sand-textured unsorted sediments. The mantle in places may be eolian sand dunes are up to 30 feet (9 meters) thick. Sand is irregular Lake 375 Lake Lake were determined from observation and sampling of outcrops, gravel pits, and construction Bertha 375 mc 375 mudflow deposits that issued from the former ice margin, but it likely is in thickness and patchy in distribution on the uplands south of Brainerd bo Star Lak375e bc 390 Lake Velvet Mud exposures; description and sampling of 220 auger borings averaging approximately 20 mostly the result of mixing windblown silt with the underlying sand and and east of the Mississippi River (Hobbs, 2001a; Knaeble, 2001). Eolian Lake Lake feet (6 meters) deep; analysis of core from 3 Minnesota Department of Natural Resources gravel through cryoturbation, bioturbation, and colluvial processes. In sand is common in Glacial Lake Brainerd deposits (unit bgl) and less 375 375 mt 0 375 mbo 39 mt rotary-sonic drill holes (two in Crow Wing County and one in Aitkin County); bridge agl 375 bc Clear 375 Big Bird pe many places the unit consists largely of reworked sand and gravel of the common in Glacial Lake Aitkin II deposits (unit ), but it is difficult Lake boring logs; water-well driller's logs; analysis of cutting samples; correlation with soil Kimble Duck Lake mc pe Brainerd assemblage, or is thin over Brainerd assemblage deposits. Contacts to distinguish eolian from lacustrine deposits, as both are composed of Lake Lake bo 375 5 pe map units (Arneman and others, 1965; Brug and Gorton, 1994; Richardson, 1997); and with Brainerd assemblage outwash (unit bo) in places are gradational or well-sorted, very fine- to medium-grained sand; thus, the mapped extent Jenkins pe 37 375 390 Stark Upper 375 Greer Bass Upper Lake aerial photograph interpretation. is highly speculative where overlying glacial lake sand. pe 390 approximately located. Deposited mostly by meltwater issuing from the Hay Lake 37 bo Lake 36 Lake Dean 5 Eastham Lake pe ice margin, but also includes sand and gravel deposited by stagnant-ice Beach ridge—Sand, gravelly sand, and sand and gravel deposited at the former 36 31 Pine 31 375 36 DESCRIPTION OF MAP UNITS 36 31 5 Lake 36 40 Lake 31 atl meltwater flowing into the western end of Glacial Lakes Aitkin I and II. margins of Glacial Lake Aitkin and Mille Lacs Lake. Ossawinnamakee 375 mt 375 5 HOLOCENE AND LATE PLEISTOCENE Lake Adney 37 Includes deltaic sediment in proximity to Glacial Lakes Aitkin I and II or Stream-cut scarp—Marks a former fluvial channel. Where paired, scarps bound bis mbo Lake 371 bc Glacial Lake Brainerd sediment. 375 bc pe er pe dl Disturbed land—Land disturbed by iron-ore mining; primarily waste rock and stream-scoured areas. Till deposits downslope of scarps are fluvially 1 375 1 6 6 Riv the formerly overlying unconsolidated sediment, including sand, gravel, mi Ice-contact stratified materials—Sand, gravelly sand, and cobbly gravel; scoured and may be mantled by sand and gravel too thin and patchy to pe 1 6 al ml 1 6 1 pe Google 390 390 till, and peat. commonly includes interbeds of, and in places is capped by, sandy to map separately. Boundaries of terrace units and alluvium are commonly 375 Lake 390 mt 375 Nelson 420 al clayey flow till and lacustrine silt. Deposits contain boulders in places. at scarps and are not shown by a scarp symbol on the map. Ticks point pe 390 375 pe River Perry Lake pe Peat and other organic sediments—Partially decomposed plant matter deposited Pine Pine Lake atl Some sediments were deposited by meltwater in fans at the ice margin; downslope. mi Little 390 pe in marshes and swamps. Includes fine-grained organic matter deposited in bc 5 pe others were deposited beneath or surrounded by ice (eskers). Individual mt 37 T. 136 N. ponded water, marl (calcareous clay) at depth in places (Schwartz, 1959), General flow direction of a meltwater stream that deposited surficial sand and Pequot 405 bc Dean deposits may consist of reworked or thinly mantled Brainerd assemblage gravel—Arrowheads point in the direction that glacial meltwater last flowed Lakes bo 375 narrow deposits of alluvium along streams, narrow beach deposits, and Lake small bodies of open water. The unit is typically found in depressions; ice-contact deposits (unit bis). within a unit. Flow direction indicators may point in opposite directions mbo mc 375 mt 375 375 pe some deposits have been drained. Most depressions are interpreted to mc Till, sand, and gravel complex—Glacial, fluvial, and lacustrine sediment in adjacent units (see sec. 23, T. 47 N., R. 29 W.). Breezy bc pe DEAN LAKE agl Sibley Horseshoe mc ml agl have formed from melting buried glacial ice along former glacial stream too intricately associated to distinguish at map scale; commonly formed Kame—Conical hill composed predominantly of sand and gravel (secs. 15 and 22, Point Lakes MISSION PERR390 Y LAKE pe Lake SIBLEY mi pe channels and as irregularities on flat, poorly drained lake plains. by the melt-out of underlying stagnant ice, causing the collapse and T. 135 N., R. 29 W.; sec. 12, T. 134 N., R. 28 W.; sec. 26, T. 138 N., R. bo bo bc T. 136 N. 390 al Floodplain alluvium—Mississippi River alluvium is generally less than 6 feet mixing of overlying sediment. Includes areas of till capped by or thinly 26 W.). Interpreted to be a deposit within the confines of supporting ice. bl al 375 atw 375 bc er Riv (2 meters) of silt loam to loamy sand including scattered wood and shell interbedded with sand and gravel, as well as areas of thin till over thick When the ice melted, the sand and gravel remained above the surrounding Pelican ml bis Deer 1 sand and gravel. Where mapped in proximity to the Nelson Lake till topography. Collapsed bedding is common. Lake pe fragments overlying sand, gravelly sand, or gravel. Some depressions 375 mt Lake deposits (unit atl) there is a thin, discontinuous cap of Aitkin assemblage agl have been filled with thick silty to clayey sediment. In places covered by Drumlin—A streamlined hill or ridge composed typically of glacial till; feature formed Fool 375 till, too irregular to show. Deposits may include incorporated Brainerd mbo thick fill in developed areas near Brainerd. Alluvium in smaller streams is at the base of moving Rainy-lobe ice. Drumlins are partially masked in Lake agl assemblage materials near the former ice margin and may also be thin or PELICAN 375 mt 6 finer-grained and typically capped by and interbedded with thin, organic- places by supraglacial sediment or eolian sand, and can also be partially 375 lt pe patchy over the Brainerd assemblage deposits in places. Contacts with 375 bc bc lt i rich layers. Contacts with other map units are commonly scarps. buried by glaciofluvial sand and gravel. Drumlins on the highlands in 360 375 other Mille Lacs deposits are gradational. issipp ld Lacustrine sediments—Sand to loamy fine-grained sand; organic-rich layers northern Crow Wing County are generally not as distinct as those south al 375 pe Cullen mi Miss occur in places and may include marl at depth (Schwartz, 1959). Gravelly mt Garrison till deposits—Silt loam- to loam-textured, unsorted sediment with and east of Brainerd, due to a thicker cover of supraglacial material. Lakes Bass 31 Indian Jack mt Lake pebbles, cobbles, and boulders. Includes small bodies of bedded sediment Arrow shows inferred direction of ice movement; the length of the arrow Lake 375 zones occur in some beach ridges. Mostly deposited when lakes were at 375 375 36 36 31 Mission lt agl at or near the surface in places. The matrix texture varies widely from is approximately equivalent to drumlin length. 375 mt pe higher levels. In places includes silt and clay deposits at depth where Twin Lougee 5 mc clayey, due to extensive local incorporation of proglacial lake sediment, to 37531 37 mbo T. 47 N. Lakes Lake 36 pe lt al mapped along the Nokasippi River (secs. 8, 9, 16, and 17, T. 43 N., R. 31 Fan deposit—Sand and gravel, interpreted to be an alluvial fan at an ice margin (sec. mc 375 sandy, due to mixing with the underlying Brainerd assemblage deposits, but ld RABBIT LAKE W.). Many deposits along the edges of lakes and bogs are too narrow to 23, T. 138 N., R. 27 W.). Lake bo WOLFORD Island be mapped at this scale. in general the till of the Mille Lacs deposits is finer-grained than typical Edna bc Lakes Lake Esker—Sinuous narrow ridge of predominantly sand and gravel; interpreted as having 6 375 atw Cromwell Formation till. bgl lt Lower terrace sediments—Sand and gravel that includes fine-grained sand, silt, been deposited in an ice-tunnel or ice-walled channel by a glacial meltwater 1 6 1 mi Rabbit 0 Coles 36 360 360 mi and organic slackwater sediments in places; consists of river-channel fluvial Brainerd assemblage—Glacial, fluvial, and lacustrine sediment of northeast (Rainy) stream. The fluvial sediment may be covered by 10 feet (3 meters) or Perch ld Lake mt mbo mt Lake deposits that now form terraces above the modern floodplain. South of the provenance (Table 1), deposited by the Rainy lobe and its meltwater more of till. Arrowheads point in the direction of transport. pe Lake pe al Carlson pe confluence of the Crow Wing and Mississippi Rivers (sec. 23, T. 44 N., R. (Schneider, 1961). Where mapped in the proximity of Mille Lacs deposits, Nisswa Lake atl Ice-walled lake-plain rim—Line marks the rim of an elevated plateau of lake sediment 375 mc 32 W.) the deposits are interpreted to be composed predominantly of Crow Brainerd assemblage sediments commonly show reworking at the top and are 360 Cuyuna interpreted to be the deposits of a former lake once walled by glacial Johnson 375 375 Nisswa Clark dl Wing River sediment. Here the rock fragment content includes about 10 to mantled in places by generally less than 10 feet (3 meters) of the Mille Lacs ice. Lake Lake Lake Roy Garden 375 Casey 15 percent carbonate rock where unleached, and only a trace amount—less deposits. Till deposits are yellow-brown (10YR5/4) to brown (7.5YR5/4) 31 Turner Lake Inferred ice margin—Approximate location of the maximum or recessional ice Lake Lake ld Lake Rice Lake Black bc 39031 than one percent—of northeastern-source red volcanic rock and sandstone. where oxidized and gray (10YR4/2 to 7.5YR4/2) where unoxidized, but Lake pe 36 margins of the Rainy and Superior lobes (modified from Johnson and Edward Silver 36 Bear 37536 North of the confluence of the Crow Wing and Mississippi Rivers the range to a red-brown (5YR5/4 to 5YR5/5) color in the Crosby–Trommald– Lake mc 405 Mooers, 1998) and approximate maximum ice margin of the St. Louis bis Lake mbo dl 5 deposits are composed of predominantly Mississippi River sediment and Riverton area, presumably due to glacial incorporation of local iron ore. LAKE EDWARDS Trommald sublobe (Fig. 2). Superior-lobe and St. Louis-sublobe ice entered the map 360 375 mt mi 37 NISSWA CENTER al 360 mbo contain trace amounts of carbonate and about 5 to 10 percent red volcanic Deposits are commonly deeply leached of carbonate materials and contain bis 46°30' area from the east, Rainy-lobe ice entered from the northeast. Lines are 46°30' Agate 1 375 rock and sandstone fragments (Knaeble, 2001). less than 5 percent carbonate where unleached. Superior provenance, red 1 6 1 6 Lake thin where the margin is speculative. bo 210 Cedar volcanic and sedimentary rock fragments commonly compose 5 to 10 T. 135 N. bo dl 390 Black 375 Lake Late Wisconsinan Deposits Broad irregular trough—Interpreted to be a buried subglacial drainage channel 5 Bass dl Crosby Lake als percent of the 1 to 2 millimeter sand fraction. 371 37 bis pe Lake Lake 360 390 (tunnel valley) or a preexisting drainage valley that was subsequently ut Upper terrace sediments—Sand and gravel deposits including fine-grained bgl Glacial Lake Brainerd deposits—Well-sorted, very fine- to medium-grained, Hubert bc filled by sediment. Ticks point downslope. Fawn 375 mbo 375 bl 375 mi sand and silt; primarily meltwater river-channel fluvial sediment of the noncalcareous sand. At depths greater than 10 feet (3 meters) sediment Lake Serpent Lake glacial Crow Wing River. Where unleached, deposits contain about 10 375 Deerwood als may contain interbedded silt and clay layers. May be interbedded with Gladstone bo mt ACKNOWLEDGMENTS Lake bo mbo Ironton mc to 15 percent carbonate rock fragments and trace amounts—less than one turbidite and deltaic sand and gravel deposited by meltwater streams of Gull bgl bo pe Lake bc percent—of northeastern-source red volcanic rock and sandstone fragments. the retreating Rainy lobe and possibly the Superior lobe as they entered Dr. Allan Schneider granted interviews and supplied samples, field descriptions, and dl Reno The Mississippi River also contributed a minor amount of sediment to the 360 the lake from the north and east. Deposited on and around large buried test data from work he did in the area a half century ago. This information was a significant pe mc 36 Spider bgl Blackhoof Lake 360 bc 375 unit from sec. 13, T. 44 N., R. 32 W. southward (Knaeble, 2001). The unit ice blocks left by the Rainy lobe. These ice blocks melted following the aid in the map compilation and is greatly appreciated. He also provided us with field Lake Lake Rice DEERWOOD 31 36 31 IRONDALE Lake is interpreted to have formed as Des Moines-lobe meltwater drained east drainage of Glacial Lake Brainerd (Mooers, 1988), leaving depressions books that Dr. Leonard Weiss compiled while a University of Minnesota graduate student. pe ld pe 390 390 T. 46 N. Round Riverton mbo through the Pillager gap (a mile-wide gap in the St. Croix moraine about in the landscape that are now lakes. Eolian sand commonly covers the Wayne Green, a former instructor at Brainerd Technical College, helped locate outcrops and Lake dl Portage 0 39 4 miles [6 kilometers] upstream from the confluence of the Crow Wing lake sediment, in places forming dunes (Hobbs, 2001a, b; Knaeble, 2001). assisted us in the field. Thanks are extended to Anderson Brothers, Hengel Incorporated, bis 375 bo Lake 6 Olanderbc and Mississippi Rivers), eroding a wide valley (Goldstein, 1985; Mooers, Glacial Lake Brainerd formed as Rainy-lobe ice retreated northeast, but Wannebo Excavating Incorporated, and all other gravel pit operators and land owners who 6 Lake 1 mbo 390 1988). As the water volume decreased, sediment refilled the scoured valley near the southern end of the county active Superior lobe ice or stagnant Hamlet gave us permission to examine exposures on their property. 1 bo Lake to the upper terrace level. Rainy or Superior lobe ice apparently blocked drainage to the south. When the ice melted, initial downcutting of the present valley of the Mississippi 360 210 REFERENCES pe bc PLEISTOCENE bo 25 360 bis bis 375 Lookout 0 390 mc River began as Glacial Lake Brainerd drained (Mooers, 1988). This unit North ld 375 39 bo Long bo Lake Aitkin assemblage—Glacial and lacustrine sediment of northwestern provenance defines the approximate extent of former Glacial Lake Brainerd. Arneman, H.F., Hanson, L.D., Hermanson, H.P., and Hilde, D., 1965, Soil survey of Crow Lake 390 bl 405 mc 390 (Table 1) deposited by ice and meltwater of the St. Louis sublobe, the most Wing County, Minnesota: U.S. Soil Conservation Service Series 1957, no. 21, 40 390 bl Lake sand and silt—Interbedded very fine- to medium-grained sand to silt, 390 390 Shirt p., scale 1:20,000. bis 390 bc bis Lake recent glacial advance into the area (Fig. 2). Very little sand and gravel with lenses of silty clay to gravelly sand, including till. Generally, finer- bis 36 Brug, W.H., Jr., and Gorton, J.F., 1994, Soil survey of Morrison County, Minnesota: U.S. 31 36 31bl outwash is found in these units, most likely because the ice advanced grained sediment occurs toward the middle and in the deeper portions pe 36 Wolf 390 bgl 375 Lake Long 6 Arbor Soil Conservation Service, 191 p., scale 1:20,000. 390 390bis mt into Glacial Lake Aitkin I (lake boundaries are approximately the same of a deposit. Coarse-grained sand and gravel may be present along unit 375 bc bl Lake 390 Lake mi 375 as Glacial Lake Aitkin II—see Nelson Lake wave-washed till deposits Loon mbo mo boundaries. Where the unit occurs on flat-topped hills (commonly with Farnham, R.S., McAndrews, J.H., and Wright, H.E., Jr., 1964, A Late-Wisconsin buried soil Horseshoe Lake Goose [unit atw]) and incorporated the underlying silt and clay lake sediment; near Aitkin, Minnesota, and its paleobotanical setting: American Journal of Science, T. 134 N. Lake bis mc Lake 390 rims at the margins), the sediment was deposited in ice-walled depressions bo 6 405 1 thus, when the ice melted, clay loam till and lacustrine sand, silt, and clay bo 6 1 pe created during the early stages of glacial stagnation. Shallow lakes also v. 262, p. 393-412. bis mbo 1 pe pe bis (including Glacial Lake Aitkin II sediment) were deposited. The till is formed in depressions scoured out by glacial ice in drumlinized areas. Goldstein, B.S., 1985, Stratigraphy, sedimentology, and Late-Quaternary history of the al Wise 375 yellow-brown (10YR5/4) to brown (7.5YR5/4) where oxidized and gray bo Lake bo Outwash—Sand, gravelly sand, and gravel; cobbly in places, especially near Wadena drumlin region, central Minnesota: Minneapolis, University of Minnesota, Eagle (10YR4/1 to 5/1) where unoxidized. Carbonate leaching depth varies but pe Bay Lake ice margins. Includes loamy, poorly sorted intervals. Mantled in places by Ph.D. dissertation, p. 171-187. pe 360 Hoppy Lake ld pe 375 bl bgl Lake 390 Clearwater is usually less than 6 feet (2 meters). Sand grains (1 to 2 millimeters) bo mo 3 feet (1 meter) or more of sandy loam- to loamy sand-textured unsorted Hobbs, H.C., 2001a, Surficial geology of the Brainerd quadrangle, Crow Wing County, bl 390 BAY LAKE and pebbles are commonly composed of 5 to 10 percent carbonate, rare to 360 sediments. The mantle is likely the result of the mixing of windblown silt Minnesota: Minnesota Geological Survey Miscellaneous Map M-112, scale 1: Mud Gilbert OAK LAWN NOKAY LAKE bo Lake mc trace amounts of gray, northwest-source shale, and approximately 2 percent Lake Lake with the underlying sand and gravel through cryoturbation, bioturbation, 24,000. bo bl ld Superior provenance, red volcanic and sedimentary rock fragments. 390 and colluvial processes, but in places the mantle may be mudflow deposits bis ———2001b, Surficial geology of the Gull Lake quadrangle, Cass and Crow Wing Twin pe 390 agl Glacial Lake Aitkin II deposits—Very fine- to medium-grained sand; laminated that issued from former ice margins. Collapsed bedding in places is due 371 390 Counties, Minnesota: Minnesota Geological Survey Miscellaneous Map M-113, 375 bgl 375 Island ml beds of silt and clay in places where the former lake was deepest. Gravel 360 Red Sand Rice Mud Lake Heron to sediment deposition on melting ice (Zumberge, 1952). Deposited by scale 1:24,000. Lake 36 31 Lake bo Lake Lake Nokay pe pe Birch T. 45 N. is found in areas where the former lake was shallow, and also within beach meltwater from the receding Rainy lobe. Includes deltaic sediment in pe Lake 0 390 pe 39 Lake ridges. Radiocarbon dates indicate that lake sediments were deposited Johnson, M.D., and Mooers, H.D., 1998, Ice-margin positions of the Superior lobe 390 proximity to Glacial Lake Brainerd sediments (unit bgl). 360 375 390 mi during Late Wisconsinan deglaciation, in Patterson, C.J., and Wright, H.E., Jr., eds., pe mo mt approximately 11,635 ± 350 years before present (Farnham and others, 390 btd mbo bis Ice-contact stratified materials—Sand, gravelly sand, and cobbly gravel; Contributions to Quaternary studies in Minnesota: Minnesota Geological Survey pe Maple 1964). pe commonly includes interbeds of sandy till and silt, and in places is capped Report of Investigations 49, p. 7-14. 1bgl 6 Brainerd Lake Whipple mc 405 als Lake sand and silt—Interbedded very fine- to medium-grained sand to silt by these sediments. Deposits may contain boulders and ice-collapse Lakbises Partridge Knaeble, A.R., 2001, Surficial geology of the Baxter quadrangle, Crow Wing, Morrison, BAXTER bgl Hanks Lake with lenses of silty clay to gravelly sand. Deposited in ponded water at bo White btd Lake 0 deformation features. Most materials were deposited by meltwater in 18 39 Turtle and Cass Counties, Minnesota: Minnesota Geological Survey Miscellaneous Map Sand 390 Portage Wilson or near the maximum ice margin (found only in secs. 2 and 12, T. 46 N., coalescing fans at the ice margin, but some were deposited beneath or Lake ml Lake Lake 360 375 Lake M-111, scale 1:24,000. 18 R. 28 W.) surrounded by ice resulting in the formation of eskers and kames. bo pe 390mc atw Nelson Lake wave-washed till deposits—Generally clayey-textured, unsorted Mooers, H.D., 1988, Quaternary history and ice dynamics of the St. Croix phase of Late r ml 390 bc Till, sand, and gravel complex—Includes areas of sandy till capped by or bl mt Wisconsin glaciation, central Minnesota: Minneapolis, University of Minnesota, Ph.D. 390 pe sediment with scattered pebbles and rare cobbles and boulders that is Perch Rive ld Grave thinly interbedded with sand and gravel, and areas of thin, sandy till over btd Rice 390 36 dissertation, p. 168-176. Lake 31 Lake 390 Lake commonly mantled by thin, sandy sediment. The surface was smoothed by thick sand and gravel. Till matrix texture ranges from loamy to very 210 36 36 31 36 31 390 Baxter al mc Round wave action. Generally more clayey with depth, but in many places the unit sandy. Contacts are gradational with other Brainerd assemblage units. Richardson, T.N., 1997, Soil survey of Cass County, Minnesota: U.S. Soil Conservation 390 pe Scott Lake 360 375 mo Lake is mostly clay due to extensive incorporation of underlying proglacial lake Glacial, fluvial, and lacustrine sediments are too intricately associated to Service, 300 p., scale 1: 24,000. pe 390 pe sediment by the advancing St. Louis sublobe. Brown in color (7.5YR5/4) Schneider, A.F., 1961, Pleistocene geology of the Randall region, central Minnesota: Kenney pe distinguish separately at map scale; commonly formed by processes at the T. 133 N. 375 mt 6 al mbo Lake between Indian Jack (sec. 34, T. 136 N., R. 26 W.) and Rabbit Lakes (sec. fluctuating ice margin, and through the melt-out of underlying stagnant Minnesota Geological Survey Bulletin 40, 151 p. 1 6 1 390 1 6 ml 1 bl 19, T. 47 N., R. 28 W.), where the till is mixed with underlying Mille Lacs ice. Particularly evident as remnant retreatal moraines. Schwartz, G.M., 1959, Investigation of the commercial possibilities of marl in Minnesota: 360 375 mo ld deposits. The outer margin of the unit roughly delineates the maximum mt bt South Long Lake till deposits—Chiefly sandy loam-textured, unsorted Office of the Commissioner of Iron Range Resources and Rehabilitation, p. 133- Island ippi mi Lake Miller extent of Glacial Lake Aitkin II. sediment that contains pebbles, cobbles, and boulders; sand and gravel 146. bis Mississ Lake Borden lt mi atl Nelson Lake till deposits—Generally clayey-textured, unsorted sediment Bass pe Upper South 375 Lake lenses occur in places. Generally consists of greater than 10 feet (3 meters) Wright, H.E., Jr., 1972, Quaternary history of Minnesota, in Sims, P.K., and Morey, G.B., Lake btd with scattered pebbles and rare cobbles and boulders. Generally more 25 Russell Long Lake pe pe al of rocky supraglacial till over dense subglacial till. Patchy, fine-grained eds., Geology of Minnesota: A centennial volume: Minnesota Geological Survey, p. Lake 390 18 bgl bo pe bt clayey with depth, but in many places the unit is mostly clay due to eolian sand mantles this unit on the uplands south of Brainerd and east of 515-547. 360 375 ld extensive incorporation of proglacial lake sediment by the advancing St. the Mississippi River (Hobbs, 2001a; Knaeble, 2001). 0 ld 390 Garrison Zumberge, J.H., 1952, The lakes of Minnesota, their origin and classification: Minnesota 36 Mille Louis sublobe. Brown in color (7.5YR5/4) where mixed with underlying CROW WING mc btd South Long Lake drumlinized till deposits—Chiefly sandy loam-textured, Geological Survey Bulletin 35, p. 18-20. LONG LAKE MAPLE GROVE GARRISON Lacs Mille Lacs deposits toward the outer ice margin; Mille Lacs deposits are 375 pe 405 mt 390 unsorted sediment with pebbles, cobbles, and boulders; sand and gravel CASS COUNTY btd 371 390 405 mc Lake at or near the surface in places. btd 390 T. 44 N. lenses are uncommon at depths greater than 10 feet (3 meters). Generally South btd 405 390 Mille Lacs deposits of the Cromwell Formation—Glacial, fluvial, and lacustrine consists of less than 10 feet (3 meters) of very sandy supraglacial till over bo 375 pe Long bc 169 dense, subglacial till. Commonly molded into elongate hills (drumlins) Lake mi mi sediment of northeastern (Superior) provenance (Table 1), deposited by the btd 405 Superior lobe and its meltwater during the Automba phase (a readvance by overriding glacial ice. Commonly overlain by a few feet (1 meter) of Jack Pine 390 mbo Lake fluvial, eolian, or lacustrine sand near outwash and lake deposits. Patchy, T. 44 N. 390 of Superior lobe ice after its retreat back into east-central Minnesota Rainy lobe fine-grained eolian sand mantles this unit on the uplands south of Brainerd 390 from its maximum advance at the St. Croix moraine during the previous pe 405 St. Croix phase; Wright, 1972; Johnson and Mooers, 1998). The till is and east of the Mississippi River (Hobbs, 2001a; Knaeble, 2001). lt 405 pe al Smith Lake generally reddish brown (5YR5/4) where oxidized and gray (5YR4/1) 390 ld Pre-Late Wisconsinan Deposits al Holt where unoxidized. Some leaching of carbonate in the till is common but bo AITKIN COUNTY Long 405 mc pwt Till—Dense, sandy loam- to loam-textured, unsorted sediment that contains ut bt pe the depth of leaching varies; not as deeply leached as Brainerd assemblage 40mc Lake Lake mbo 5 390 till; sand and gravel deposits of both assemblages are deeply leached. pebbles, cobbles, and boulders. Carbonate pebbles are present. May be an St. Louis 0 mt 360 36 31 36 31 36 31 36 31 46°15' sublobe 46°15' btd 39 Unoxidized and unleached deposits seldom contain more than 2 percent incorporated thrust slab of older Winnipeg-source till that was excavated 390 Superior pe mi mi bc 36 carbonate grains. Superior provenance, red volcanic and sedimentary rock by Rainy-lobe ice, or this material may be an isolated remnant of old till lobe fragments commonly compose 10 to 20 percent of the 1 to 2 millimeter exposed following the last glaciation. Occurs only in secs. 19 and 30, T. 405 pe Crow sand fraction, and dark igneous and metamorphic rock fragments generally 43 N., R. 31 W. lt Wing 1 6 1 6 1 6 1390 6 1 bt Camp compose greater than 20 percent. The Mille Lacs deposits contain similar Lake bl btd Lake 375 pe sand and pebble provenance indicator minerals to other Cromwell Formation 360 375 bc btd 375 pe 375 deposits, but the till commonly contains more silt and clay because the COUNTY al mbo mc 5 River pe 40 N 0 mt pe glacier that deposited it advanced through a proglacial lake and incorporated mbo 39 Mud 375 bc ISO the underlying lake sediments. btd 0 Lake mbo 39 Nokasippi ml ml Lake sand and silt—Interbedded very fine- to medium-grained sand to silt Des Moines lobe Round mc mc mbo al MORR bt with lenses of silty clay to gravelly sand, including flow till (mudflow Lake 375 bc FORT RIPLEY 360 ROOSEVELT sediment). Generally, finer-grained sediment occurs toward the middle PLATTE LAKE mt ST MATHIAS DAGGETT BROOK bis pe 390 mc ld 0 390 Whitefish 39 Erskine and deeper parts of the deposits. Coarse-grained sand and gravel may pe Lake Twentytwo Lake 375 Lake pe be present along unit boundaries. Where the unit occurs on flat-topped mbo bc T. 43 N. Brook T. 43 N. hills (commonly with rims at the margins—see ice-walled lake-plain rim mi mi bis btd pe al bt ett btd symbol), the sediment was deposited in ice-walled depressions created bo Figure 2. During the last glaciation, the Late Wisconsinan, Crow 360 Dagg Mud ml during the early stages of glacial stagnation. Where the unit is mapped al mbo 390 pe al Lake Bass mt Wing County was completely covered by ice of the Rainy lobe, which al Lake in lower-lying areas, the lakes in which the unit was deposited formed at 405 moved into the county from the northeast. Following the retreat of pwt 390 the ice margin or in later stages of stagnant-ice melt-out. Mud bo bt the Rainy lobe, the Superior lobe moved into the county from the east 390 390 mo mo Outwash—Sand, gravelly sand, and gravel; cobbly in places. Deposited by 360 Lake pe mc (the line of maximum extent of the Superior lobe is dashed where 360 390 Bulldog mt meltwater from the receding ice margin. Includes deltaic sediment in the pe pe Lake pe buried by later advances). Lastly, ice originating northwest of Crow bt btd Rock vicinity of Bay Lake. The highly irregular surface expression of the unit 390 mbo Lake Wing County formed the St. Louis sublobe, which also flowed into Sebie bc 390 is due to local sediment collapse caused by ice-block melt-out. Platte the county from the east. Lake mbo360

ut COUNTY LACS MILLE lt pe Lake 405 bc btd mc pe 36 375 btd bis bt mo 31 31 pe 36 31 36 375 36 375 390 31 mc 345 bt 375 pe 36 Long Hannah bo Lake Lake R. 32 W. 94°15' R. 31 W. R. 30 W. 94°00' R. 29 W. R. 28 W. MORRISON COUNTY Table 1. Physical characteristics of glacial deposits in Crow Wing County.

Digital base modified from the Minnesota Department of NORTHWEST NORTHEAST Transportation BaseMap data; digital base annotation by PROVENANCE WINNIPEG RAINY SUPERIOR the Minnesota Geological Survey. Every reasonable effort has been made to ensure the accuracy of the factual data on which this map GIS compilation by R.S. Lively Figure 1. The map units from the 1:100,000 surficial map Lobe St. Louis Rainy Superior Elevation contours were derived from the U.S. Geological interpretation is based; however, the Minnesota Geological Survey does not warrant or guarantee and Joyce Meints have been combined into three simplified material units: Brainerd Survey 30-meter Digital Elevation Model (DEM) by the SCALE 1:100 000 that there are no errors. Users may wish to verify critical information; sources include both the refer- Edited by Lori Robinson unsorted sediment or till (green), sand and gravel (orange), TILL TEXTURE ...... Loamy to clayey ...... Sandy ...... Silty to loamy Minnesota Geological Survey. ences listed here and information on file at the offices of the Minnesota Geological Survey in St. Paul. TILL COLOR 1 0 1 2 3 4 5 MILES In addition, effort has been made to ensure that the interpretation conforms to sound geologic and and lacustrine fine-grained sand, which in places contains or Oxidized ...... Yellow-brown to ...... Brown ...... Red-brown Universal Transverse Mercator Projection, grid zone 15 cartographic principles. No claim is made that the interpretation shown is rigorously correct, however, overlays silt and clay (blue). Water bodies are white. brown 1983 North American Datum 1 0 1 2 3 4 5 6 7 8 KILOMETERS and it should not be used to guide engineering-scale decisions without site-specific verification. Unoxidized ...... Gray to dark gray ...... Gray to brown-gray .....Gray to red-gray PEBBLE TYPE CONTOUR INTERVAL 15 METERS Carbonate ...... Uncommon ...... Absent to rare ...... Absent to rare ©2004 by the State of Minnesota, Department of Natural Gray-green rock ...... Uncommon to ...... Uncommon to ...... Common to common common abundant Resources, and the Regents of the University of Minnesota Red felsite ...... Absent to uncommon ..Uncommon ...... Common LOCATION DIAGRAM The University of Minnesota is an equal opportunity educator GEOLOGIC ATLAS OF CROW WING COUNTY, MINNESOTA Gray shale ...... Absent to rare ...... Absent ...... Absent and employer