MAP 508 • 2021 Bedrock geology of Dodge County, Wisconsin DODGE COUNTY Esther K. Stewart

88°30' 88°45' 88°37'30" 88°52'30" 6 EXPLANATION OF MAP UNITS Tunnel City Group, undivided (Furongian; 0–155 ft) FOND DU LAC CO 630 40 89°0' 6 ! 6 20 ! 10 !! ! ! A W ! ! 1100 W ! GREEN LAKE CO ! ! ! WW ! ! ! ! DG-92 ! ! ! 1100 B W! Includes Lone Rock and Mazomanie Formations. These formations are both DG-53 W ! «49 ! CORRELATION OF MAP UNITS !! ! 7

! !W ! ! 43°37'30" R16E

_tc EL709 DG-1205 R15E W R14E R15E DG-24 W! ! 1 Quaternary ! 980 ! W W 1 ! ! !

6 DG-34 6 _ ! 1 R17E Os Lake 1 R16E 6 interbedded and laterally discontinuous and therefore cannot be mapped 1 6 W ! ! 1100 !! 175 940 Waupun DG-51 ! 980 «

Oa ! R13E 6 Emily R14E W ! 43°37'30" ! ! ! 41 ¤151 B «49 ! ! ! ! Opc ! Drew «68 ! W ! East ! ! ! individually at this scale in Dodge County. Overlies Elk Mound Group across KW313 940 ! ! ! ! ! ! 940 ! W B ! ! - ! ! W ! ! ! ! ! ! !! Waupun ! W ! Undifferentiated sediment ! ! W! B 000m Cr W! ! º Libby Cr ! 3 INTRUSIVE SUPRACRUSTAL 3 1020 ! ! Waupun ! DG-37 W ! ! º 1020 a sharp contact. W ! 50 50 N ! ! KS450 ! ! ! IG300 ! B B Airport ! RO703 ! ! Brownsville ! ! ! ! ! ! 1060 ! ROCKS W ! ! ROCKS Unconsolidated sediments deposited by modern and glacial processes. 940 ° ! Qu ! W Br Rock SQ463 B ! Pink, gray, white, and green; coarse- to fine-grained; moderately to poorly 980 B River B B ! ! KT383 ! ! Generally 20–60 feet (ft) thick; ranges from absent where bedrock crops ! !! ! ! ! ! ! Su Lower Silurian ° ! ! ! ! ! 940 860 ! ! ! ! ! ! ! ! ! ! sorted; glauconitic sandstone, siltstone, and mudstone with variable W ! B B B ! ! ! 980 ! ! ! 780 ! Kummel !! out to more than 200 ft thick in preglacial bedrock valleys. Shown in cross ! SQ433 Lomira B Om unconformity 443.8 Ma ! Delbern Acres ! SQ493 carbonate cement. Glauconite concentrations are generally less than 3 ! ! ! 900 10 ! Nasbro DG-42 sections only. ! ! ! ! Cr ! ! B B AZ437 B 940 ! 900 980 ! ! Om Oa _ ! GE457 ! Oa !! lto PlumCHESTE Cr R Creek W TE754 percent but locally 15–20 percent and are especially concentrated along 860 ÇW W 9 B ! A ! ! ! ! 1060 4 !!! DG-1118 ! Upper Ordovician 0 ! ! 940 ! ! ! LEROY B ! W! ! W 900 ! ! ! ! ! Os ! ! ! ! B Ç B scoured surfaces and immediately overlying centimeter- to decime- 4 Oa B B B ! ! ! W DG-1384 ! !!! TV522 A ! 900 ’ Silurian ! !! 458.4 Ma 980 ! ! Oa ter-scale, medium- to coarse-grained sandstone beds. Exhibits predomi- Cr ! 980 1100 ! H Middle Ordovician ! 1020 a ! ! Su r FOXL!! AKE O LOMIRA nant mottled texture of probable microbial origin; lesser high- and low-an- Oa ! Fox Lake B 1020 unconformity 470.0 Ma Oa Bb ! 900 ! R ! (Llandovery, Aeronian; 0–250 ft) B !!!! ! 860 ! 1060 900 Dolostone, undivided m ! ! ! ? ! º I ! ! ! ! a ! !! 980 ! ! ! LeRoy B Opc ! Lyndon ! W C ! ! ! ! Opc gle crossbedding with abundant coarse-grained glauconite concentrated C !! !! ! ! ! ! Lower Ordovician B ! ! ! ! ! ! ! ! ! ! ! 1020 W B ! ! O Dale ! Lomira Cr PALEOZOIC ! ! ! N B Knowles Light-gray dolostone and shaly dolostone; locally fossiliferous with !!!!! ! B DG-1009 940 485.4 Ma along crossbed foresets within intervals of coarse-grained sandstone; W !! 68 ! unconformity Su 900 B ! « ! ! TRENTON !

!! ! B !

DG-1132 Cr Irish ! ! !! !!! ! B 980

brachiopods, corals, and gastropods; chert nodules common near base. ! ! ! 980 ! _ meter-scale intervals of mottled beige and green sandstone through mud- ! ! ! ! DG-1401_ ! t ! ! ! !! 900 ! ! W

Os 820 ! 980 ! _ Exposed in isolated ledge-forming outcrops along edge of Niagara W HORICONNATIONAL ! ! ! ! !! Upper Cambrian 900 Fox 980 Atwater ! ! ! ! Ç4 15 ! ! ! ! stone likely caused by bleaching (oxidation) from secondary fluid flow. A ! ! B B B ! ! _tc ! ! 980 W ! ! ! Farmersville ! (Furongian) Oa ! Lake ! ! 7 ! _ ! ! «175 Opg ! 860 ! Ç 900 Escarpment; locally deeply incised by east-west-trending bedrock channels ! distinct red, tan, and gray; laminated; slightly burrowed mudstone to fine- W! ! 36 Os W Mill Cr 980 ! WILDLIFE REFUGE ! Cr ! ! ! «33 ! ! DG-39 ! Gill 41 unconformity 47.0 Ma infilled with several hundred feet of unconsolidated sediments. Overlies ! ! 31 STATETHERESA WILDLIFE MARSH AREA _ grained sandstone bed (about 1 ft thick) was identified toward the base in ! B 940 ! Os 36 MA 900 36 31 860 ew ! ! B - Cr ! B ! ! 36 31 36 31 ! ! 940 ! ! ! the Maquoketa Formation across a sharp contact. 31 ! R RJ807 T13N Middle Cambrian multiple boreholes in Dodge and Columbia Counties. ! Mill ! ! _e _ee ! ! B ! ! Ç ! ! ! SH !! ! 940 ! ! ! ! _ 900 T13N W Os ! 900 T12N (Epoch 3) ! B 3 ! W! B 1020 ! ! 900 DG-1399_Ç5 ! ! 28 _ T12N Oa W 4 ! ! « em 820 ! ! ! ! Randolph 1 ! 940 ! ! 6 ! Os !!!!!!! ! 6 1 6 ! Ordovician Elk Mound Group 6 W 1 6 1 B 820 1 unconformity ! ! ! ! ! MW899 ! ! ! !! ! ! ! ! ! ! ! ! !! (Epoch 3 to lower Furongian; uncertain maximum thickness) ! ! 780 ! ! ! Ypm 940 KM694 ! B ! ! B ! ! ! ! ! MESOPROTEROZOIC !! ! ! ! ! 900 Theresa Station ! Fox Lake ! ! ! Kekoskee XG858 Su 900 ! ! Ç ! ! (Upper Ordovician, upper Katian; 0–270 ft) ! ! ! ! ! Maquoketa Group, undivided B ! ! ! ! ! ! Junction ! ! ! W! ! ! ! !! Su ! 860 Includes Wonewoc, Eau Claire, and Mount Simon Formations. 3 W ! Kekoskee ! 780 DG-12 3 Ç ! ! 40 ! ! B ! 40 ! ! Millpond 900 ! ! W ! ! 780 ! ! Slope-forming unit along edge of Niagara Escarpment. Includes Neda, ! ! ! B! ! W !! ! ! DG-136 Paleoproterozoic to Mesoproterozoic Baraboo interval sediments across a ! ! W B Yw Om ! !! ! ! ! ! ! ’ ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! «28 «67 W 780 unconformity 130 Ma ! ! ! ! ! ! ! ! W ! Brainard, Fort Atkinson, and Scales Formations. Uneroded thickness ! ! ! ! ! ! ! 820 ! ! ! 900 B ! nonconformity; grades laterally into Parfreys Glen Formation near elevated ! B Ç ! ! PALEOPROTEROZOIC ! ! ! !!! ! ! ! e ! ! !! XYi !! a Theresa ! XYb v 860 ! ! ! «26 ! W W ! !! e ! ! ! ! ! W to MESOPROTEROZOIC between 180 and 270 ft. Overlies Galena Formation of Sinnipee Group ! ! r Ç ! 900 !! ! ! areas in underlying Precambrian surface. Variations in thickness are mostly ! !!! ! ! ! DG-15 ! 33 900 ! « W 151 ! 820 FinkOm Cr ! ! ¤W ! ! ! ! ! B ! ! SouthRandolph ! ! across a sharp contact. ! ! ! D W W ! ! ! W! accommodated by Mount Simon Formation and reflect variations in topog- ! ! a W ! WILLIAMSTOWN ! 1710 Ma ! ! !! ! W B ! ! ! m 940 ! Brook ! !!!! Burnett ! Su ! ! ! ! !! ! ! ! ! ! !!W ! ! ! Buckhorn Corner Spring !! ! !! 43°30' Opc Os ! ! ! ! ! ! B raphy of underlying Precambrian surface. Shown in cross sections only. ! ! ! ! ! ! ! 820 Neda Formation (0–30 ft). Red, hematitic, dolomitic, and goethite-bearing !! ! !! ! ! ! ! ! ! ! !!! 860 DG-46 W 900 ! !!! ! ! ! ! !! !! ! ! ! ! ! B ! !! ! ° ! ! ! ! ! ! L !!!! ! HORICON MARSH W ! W mudstone to oolite. Lenticular, laterally discontinuous beds. ! !! ! ! Mayville ! ! 940 43°30' ! ! a ! !!! ! !! ! ! ! _e Undivided (absent to more than 460 ft). ! ! !! !! W B 860 ! ! k ! !! ! ! 900 ! !! ! ! ! ! ! ! ! !! ! DG-1398 e ! ! Sunset ! ! ! ! W W STATE WILDLIFE AREA ! !! ! Ç ! 900 860 ! ! Brainard Formation (80–100 ft). Light-gray to green, dolomitic shale and ! ! !! 4 Beach ! ! ! ! ! ! Wonewoc Formation (0–100 ft). White to pink, medium- to coarse- ! ! ! ! BURNETT ! ! ! ! W! ! THERESA B !

! 860 ! !

_ew ! Ç ! ! !!!! ! ! ! !! ! ! _ ! lesser shaly dolomite and grainstone. ! ! !!! !!! ! grained, well-rounded, well-sorted, texturally and compositionally mature ! !!! ! ! ! DG-1061 ! 860 940 ! ! ! ! ! ! W ! ! ! ! 900 ! ! !! B 4 980 ! ! Beaver W Os ! 4 B ! ! WESTFORD ! ! ! Fort Atkinson Formation (10–15 ft). Light-gray to green, shaly dolostone. quartz arenite. Characterized by high- and low-angle crossbeds, planar 860 ! ! ! ! Edge ! ! ! ! ! ! ! ! ! ! ! ! beds, and internally structureless beds. Centimeter-scale quartzite pebbles Opc ! ! Su !! ! ! ! Locally fossiliferous with thin (centimeter-scale) beds of fossil hash, espe- ! 820 ! 980 ! 860 Crystal ! B _ ! ! 3 ! ! ! ! ! ! ! !! ! ! Oa !! 940 ! ! ! ! ! ! ! ! ! ! ! ! ! locally overlie scour surfaces; localized abundant sulfide mineralization ! ! ! ! B ! ! ! 980 cially towards base. ! ! ! ! ! _! 1020 ! ! W ! ! !! ! 7 ! SYMBOLS !! ! !! ! ! ! W! ! !! ! 28 W !! ! 36 « 900 B 860 900 W W! ! ! ! 31 ! «67 36 175 940 « and associated calcite cementation are concentrated along high-angle ! W ! ! ! !! ! !! 36 ! 31 ! ! ! W ! ! B !! Beaver ! !! ! ! 36 31 º Su Scales Formation (110–150 ft). Dark-gray to green shale. Locally fossilifer- 31 ! 36 ! ! !! ! ! ! !!! ! ! Ç ! ! 31 ! ! ! ! Cr ! ! ! ! Cr ! COLUMBIA CO ! W ! ! ! !!! ! ! ! ! 1100 ! ! ! ! ! T12N ! ! !! !!! ! ! ! fractures and disseminated throughout the sedimentary matrix. The 860 ! Dam !!! ! ! ! !! ! !! ! ! 1020 ! ! !!!! ! Rolling Prairie Ç ! ! B ! Lost ! !!W! ! ! 980 ! ! ous with thin (centimeter-scale) beds of fossil hash. ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! Hochheim T11N Contact—Concealed beneath unconsolidated Quaternary T12N! ° ! ! W ! ! 1020 ! ! ! ! Horicon ! ! ! !Lake! ! ! ! ! ! Cr ! ! Sauk II–Sauk III unconformity, present in upper Wonewoc Formation ! !!! !! ! ! ! ! ! ! Om ! ! !! ! !Crystal ! ! Name W ! ! ! ! ! ! 1060 ! Os ! ! ! ! ! 900 T11N ! ! Minnesota ! ! ! sediments throughout map area. In cross sections, ! W ! 4 ! W ! Lake 1 6 W ! 1 ! !! ! ! ! 1 No (Runkel and others, 1998), is evident in drill core by an abrupt increase in ! DG-1388 ! W W !! Om 1140 6 !! ! ! 1 !6 ! Junction ! ! W ! !! ! ! Su Sinnipee Group, undivided ! WGNHS Slinger ! 6 ! W Park ! W ! 1 ! 1140 ! 6 ! ! ! ! ! ! ! ! solid where well control exists, dashed where inferred; !! ! !! ! grain size and higher concentration of heavy minerals. Overlies Eau Claire «33 W! ! 33 ! ! ! W! ! « B ! ! ! «33 ! ! ! ! ! W (Upper Ordovician, upper Sandbian to upper Katian; 0–230 ft) ! ! Ç ! ! ! ! ! ! ! ! 980 ! ! !! ! ! ! ! ! internal bedding indicated by long dashed lines. ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! 860 ! !! ! ! ° ! ! ! 980 Formation across a gradational contact. Lost ! !! ! ! ! W ! ! 820 ! ! r Ç ! !! ! ! W !! ! ! ! ! ! ! ! e !!! ! Lake ! !W ! ! ! ! B ! ! ! v Includes Galena, Decorah, and Platteville Formations. Platteville Formation ! ! ! ! B ! ! ! ! !! ! ! ! ! 900 i ! ! ! ! ! ! Os «73 !!! ! ! ! ! ! W! ! ! ! 900 !! !! 3 ! South!! !!! ! ! ! ! W R Karstens ! 3 Eau Claire Formation (0–150 ft). White, fine- to medium-grained sand- 30 ! ! W ! ! ! ! 30 ! ! ! ! ! ! ! k ! crops out in western Dodge County; Galena and Decorah Formations _ee ! ! Beaver ! ! ! Pond ! W ! DG-1130 ! 860 c ! !!! ! ! Dodge W ! 4 ! !! ! Oa Ç ! ! ! ! Anticline—Concealed. Solid arrow, where stone with common discontinuous, gray or green, millimeter- and centi- ! ! Dam ! ! ! ! ! County ! Ro ! ! ! 1100 are present but poorly constrained by well cuttings. Uneroded thickness ! r ! ! ° ! ! Ç !! ! ! !! ! ! ! !! Airport «33 C ! present, indicates direction of plunge. meter-thick silt to clay laminations. Overlies the Mount Simon Formation ! ! 1060 ! ! Os ! ° r ! Cr !! ! ! ! e ! between 200 and 230 ft. ! ! ! ! 860 ! ! v B Neda ! i ! B ! ! ! ! ! l ! across a gradational contact. Well construction reports indicate fine- ! ! ! ! O ! ! ! Lentz Cr! ! ! !! ! 900 !! ! ! ! !

Galena Formation (maximum 160 ft). Gray to beige, fossiliferous ! ! ! ! OAKGROVE ! ! ! ! B 780 ! ! !

grained fraction increases in eastern Dodge County. ! ! ! ! ! ! ! B ! ! ! CALAMUS Shultz ! ! ! ! ! Herman Center ! ! SHAW MARSH ! B ! ! ! ! ! ° ! B ! ! ! ! ! Limestone Syncline—Concealed. Solid arrow, where

! 1060 ! dolostone. ! Os ! ! ! ! ! ! ! ! STATE WILDLIFE AREA ! ! ! !!!

! ! ! ! ! ! ! 820 ! 980 º º Mount Simon Formation (absent to more than 250 ft). Similar to ! !! ! ! B ! ! ! ! ! !! ! present, indicates direction of plunge. _em B BEAVER!! ! DAM !! ! ! 860

Os ! !! ! ! ! !

Decorah Formation (absent to less than 10 ft). Silty dolostone. B ! ! HUBBARD ! ! ! ! ! JuneauW ! Wonewoc Formation. Locally includes discontinuous, gray silt laminations. ! ! ! Neda Cr HERMAN ! º !! ! !W WW ! !! Cr B ! ! ! ! W ! ! ! ! 1060 1020 ! ! ! B ! WW ! ! !! ! Indistinguishable from Wonewoc Formation where Eau Claire Formation is Leipsig ! !1020 Platteville Formation (40–60 ft). Gray, yellow, and beige; fine-grained ! ! ! !! ! ! ! ! ! B ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! Iron ! ! ! ! !! ! ! ! 780 W ! Bedrock surface elevation contour—Drawn on surface absent. ! ! DG-1402 820 dolostone. Internally structureless to planar-laminated dolostone includes ! ! ! ! 860 ! ! 4 ! Ridge 820 ! ! ! ! ! ! ! ! ! of concealed bedrock units. Contour interval 40 ft. ! ! «26 ! ! molds and casts of brachiopods and lesser trilobites, gastropods, cri- B ! !

! ! ! ! ! !!!!

820 ! !! ! ! ! ! ! (Epoch 3(?) through Lower Ordovician(?); 0–10 ft) B ! ! Oak ! ! ! Huilsburg

WASHINGTON CO Parfreys Glen Formation ! º noids, and cephalopods. Displays common millimeter-scale, dark-gray, ! ! ! ! ! ! ! B Brook ! ! !!! Grove B ! ! Butler Cr ! ! !! Wildcat Cr ! ! w S ! ! 36 ! a Os 31 ! i ! ! wavy, discontinuous silt laminations and scour surfaces; common to rare, ° ! ! n ! ! ! Pebble to cobble conglomerate. Rounded to subrounded quartzite B h !! ! i 36 31 ! 1020 Niagara Escarpment—Approximately located «73 S ! ! ! s _Opg 36 31 ! 31 ! s ! 1100 43°22'30"

31 ! B 36 !! ! i Om ! ! ! 36 ! ! p ! ! ! 1060

millimeter- to centimeter-scale, ovoid burrows in thicker silt laminations; ! ! ! ! ! ! 900 ! ! pebbles, cobbles, and boulders (4- to 6-ft diameter) in coarse- to medi- ! ! ! ! p ! ! T11N !! !! ! º Os ! ! i ! ! !! !!! ! ! 151 ! L ! ! 43°22'30" ¤ LOWELL ! ! ! ! ! ! T10N ovoid, mud-lined burrows in fine-grained, mottled to relatively structure- ! ! ! a ! ! Woodland ! ! ! um-grained sandstone matrix. Beds are massive to lenticular, 3–5 ft thick. ! ! !! C T11N !! ! ! k ! Woodland Cr ! ! ! ! ! ! !! ! ! 1060 _ ! e ! ! ! ! ! 5 less dolostone matrix; and centimeter-scale beds of fossil hash. Crops out ! ! !! ! Strike and dip of bedding Exhibits high-angle crossbedding in sandier intervals. Locally present T10N ! ! ! ! 1 North ! ! 860 ! ! Oa ! ! ! 6 B 1 ! ! ! B D ! ! 6 1 ! e ! 820 ! 6 860 ad !

1 6 Lowell ! 1 ! !

as thin (decimeter- to meter-scale), laterally continuous, tabular beds that C ! !! ! overlying high-elevation Precambrian quartzite bedrock. Lower contact is Oa ! r ! ! ! ! G ! !! !! !! ! ! ! Oa ! ! 6 ! ! ! ! ! ! ! ! ! ! locally cap isolated bedrock plateaus. Overlies St. Peter Formation across a ! ! ! ! !! an angular unconformity with Precambrian Baraboo interval rocks; upper ! ! !!!!! ! ! ! ! !! 980 82 Os ! ! ! ! ! Su Strike and dip of foliation ! ! !!! ! ! ! !! ! sharp contact. !! 780 ! 980 contact is gradational with overlying Cambrian units (through Jordan ! ! ! ! ! ! ! ! ! ! ! ! ! TT893 ! Hustisford !! !

! ! ! ! ! ! ! ! ! ! ! W

! ! ! ! !! ! ! Formation) and possibly with Ordovician Oneota Formation based on !! ! ! 780 ! ! ! W 940 3 ! HD610 º W ! ! 3 20 ! ! ! DG-1392 !! ! ! ! W! ! ! 20 !! ! ! ! ! ! !! ! ! ! W ! ! !! 4 DG-1395 ! ! !! Ancell Group, undivided !! ! Opc ! ! ! ! ! ! ! ! observations of this contact about 50 miles to the west in Sauk County ! 4 ! ! ! ! !! ! Passive seismic sampling point 820 OH482 ! ! ! ! Su ! !! !! B ! ! ! 900 ! ! ! ! !

! ! ! ! Rubicon ! (Middle to Upper Ordovician, upper Darriwilian to lower Sandbian; 0–170 ft) 740

! ! 1020 (Clayton and Attig, 1990). Shown in cross sections only. ! !! ° «60 Mill ! W ! ! Os ! Lowell CLYM! AN ! Pond ! ! ! ! He ! ! ! ! ! ! !! pp Cr ! ! ! Includes Glenwood and St. Peter Formations. St. Peter Formation crops out Astico ! ! !!! ! ! ! ! ! ! Oa DG-59 W !! ! ! Oa ! ! !!! DG-1401 ! «60 ! ! ! RUBICON Drill core hole and identifier ! ! Clyman !! ! ! ! ! ! !! Opc ! W ! ! ! ! 4 ! ! ! ! ! ! ! ! ! in western Dodge County. Glenwood Formation is present but known only ! ! ! 900 ! Mesoproterozoic «60 ! ! JunctionW ! ! ! ! ! ! ! Os «67 ! ! 900 ! R ! ! ! ! from well cuttings. 780 ! ! ! h 820 ! ! ! ! ! ! ! 860 HUSTISFORD s ! ! ! ! ! ! ! ! ! ! 820 ! !! ! 860 ! fi 740 ! ! ! !! (uncertain age) ! ! ! Pegmatites and mafic intrusions ! ! 780 860 ! ! ! ! ! ! ! ! ! Quarry ! ! ! ! Casper Cr ! ! !! ! !! ! ! Glenwood Formation (less than 10 ft; locally may reach 20–30 ft). Danville !! ! ! ! ! !! Oa ! Pratt Cr ! ! ! ! ! ! Oa ! ! ! 740 ! ! ! ! Craw ! ! ! ! ! ! KM212 ! ! !!!!!! Os ! ! ! !! ! ! 780 700 W ! Pegmatites likely related to the Wolf River batholith (about 1.46 million ! ! Clyman ! ! !Neosho! ! Carbonate-cemented sandstone to sandy dolostone. ! ! ! ! ! ! ! ! Ypm !! W ! ! ! ! ! 940 ! ! ! ! ! ! ! W ! ! Neosho ! ! ! ! ! ! ! ! years old, or Ma), part of the Eastern Granite-Rhyolite province (1.50–1.44 W ! ! ! ! ! ! ! ! ELBA ! ! !! ! KW313 ! MY146 ! ! ! ! ! ! ! !!! ! Millpond ! St. Peter Formation, undivided (0–165 ft). Consists of Tonti and Readstown ! ! Well where construction report is available; 820 ! Reeseville ! !! Saylesville ! ! ! ! ! ! Ma; see Bucholz and others, 2005; Bickford and others, 2015; Holm and ! ! ! ! ° ! ! ! ! !! ! ! ! identifier provided if used on cross section Members. Members are present as laterally discontinuous interbedded Yw ! 860 ! ! 820 ! ! 900 ! 900 820 others, 2020). Mafic intrusions of uncertain affinity; may be related to the W ! ! ! ! ! W! ! Opc ! lithofacies. Overlies Prairie du Chien Group or Trempealeau Group across a ! DG-447 ! 780 t ! ! ! ! ! 820 36 ! Wolf River batholith or the Midcontinent Rift (about 1.1 billion years old, 780 ME872 31! 36 31 ! 36 ! 900 ! ! ! ! 31 sharp, erosional, and unconformable contact. Locally may exceed 250 ft in 36 ! ! ! W ! ! 36 ! ! ! ! ! 31 ! ! t or Ga). Mafic dikes and pagmatites are reported from Waterloo quarry in ! ! Well with geophysical logs or geologic log of drill 740 ! ! ! ! ! T10N W 31 !! ! ! ! ! ! Ç !! ! northeastern Dodge County. 820 ! ! !! _ ! ! ! Cr ! ! ! ! ! ! ! southeastern Dodge County. These units are mostly inferred from regional T10N ! ! B ! T9N n cuttings; identifier provided if used on cross section 860 45 ! ! ! Nolan Cr Çaker Cr ! ! ! ! !! ! FY130 a Silver Cr ! ! 900 Mud ! Os ! !! T9N ON374 ! ! ! ! —Tonti Member (0–150 ft). Gray, white, beige, yellow, orange, and red; m ! ! ! Yw ! ! Collins

aeromagnetic data and geochronologic and geochemical data that indi- ! ! ! Om

! ! ly G 1 ! B ! ! ! 6 900 Lk ! W ! 26 6 « C ! Oa 1 900 ! ! Run 1 medium- to coarse-grained; well-rounded; well- to moderately well-sorted 1 6 ! ! ! ! 1020 cates alteration of Baraboo interval metasediments during emplacement of 6 _ 1 ! 860 6 ! 48 ! ! ! ! 82 ! 860 ! W Yw ! ! ! ! Well or drill hole in cross section 740 860 sandstone. Exhibits high- to low-angle crossbedding, fine (pinstripe) ! B 940 Wolf River batholith (Bucholz and others, 2005; Medaris and others, 2019; ! Os! ! ! ! ! ! ! ! ! ! ° Su ! ! ! ! ! ! ! ! W DANE CO ! 820 ! !!!! ! laminations, or is internally structureless. Other features include common Yw ! Holm and others, 2020). Shown in cross sections only. ! ! ! Yw ! ! ! ! ! ! ! ! 820 ! ! ! ! ! Mud Cr ! ! ! ! ! ! 860 ! ! 820 ! soft-sediment deformation; common decimeter-scale, brittle slumping of 820 ! ! ! Lebanon ! ! ! !!! ! ! ! ! ! ! ! Fault—Arrow shows sense of relative Opc ! ! Í ! ! ! ! ! 3 000m RX722 ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! 10 N 3 ! ! ! ! ! crossbedded and internally structureless strata; and localized millimeter- 10 ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! movement. Shown only in cross section. Mesoproterozoic to Paleoproterozoic ! ! ! 43°15' ! ! t ! ! to centimeter-scale sulfide mineralization disseminated throughout the ! ! ! ! 780 ! ! EMMET ! tc ! ! 740 ! ! ! ! ! ! 820 ! ! ! ! 860 ! ! 900 PORTLAND ! ! ! ! !! ! LEBANON 43°15' ! ! ! 780 matrix and concentrated along bedding planes, fractures, and brittle slump ! Yw ! ! 940 ! ! Baraboo interval metasediments, undivided ! ! ! ! !! ! ! ! 740 Lau Cr !! ! ! ! ! 820 ° !! ! ! ! ! ! !! ! 700 ! !!! Ç ! planes. Locally intercalated with centimeter-scale beds of poorly sorted !! !! W ! ! ! 740 STATE WILDLIFE AREA ! ! ! ! ! ! !! ! ! ! (younger than 1,710 Ma; uncertain maximum thickness) ! ! ! ! ! ! ! ! ! ! Oa ! !! ! ! ! ! !! ! ! Ç ! Richwood! ! ! Os ! clay to silty sandstone. Prevalent at top of St. Peter Formation, locally t 700 DG-1389 ! ! ! ! ASHIPPUN ! 740 4 ! ! D ! ! ! a Su ! ! ! ! ! !!!!! ! ! wso 940 Includes at least two units in Dodge County: Waterloo Quartzite and an ! Mud L ! ! ! !!! ! ! ! ! ! ! !! ! ! ! ! ! !! ! absent. Gradational contact or interbedded with Readstown Member. XYb MUD LAKE ! ! ! ! 780 ! 740 ! !! ! Sugar ! n ! ! 900 860 ! ! ! ! ! ! ! Cr ! Oa ! ! ! ! ! ! ! unnamed iron-formation. The nature of the contact between the Waterloo ! ! SHIELDS ! RW401 ! ! ! 900 ! ! 780 ! ! Island Oa ! ! ! ! Ol! d !! !! ! !

! ! B ! ! !!º ! !! ! ! ! ! ! ! ! ! ! ! ! ! !!!!!!!!! !

! 820 ! ! !! ! ! !!!! ! ! ! ! !! Lebanon ! ! ! 860 !! !!!!! ! ! ! —Readstown Member (0–86 ft). Gray, red, and green clay; siltstone; and ! ! ! ! !!! !!!!!! Old ! AH348 ! ! ° !!! !!!!!!!!!! ! ! Quartzite and underlying units is unconstrained in Dodge County and !!! !! ! ! ! 820 ! !!!!!!!! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! ! ! !!! ! Ashippun ! ! Chub Opc ! !! ! ! ! !! ! ! ! ! ! 820 ! ! ! ! NQ391 Om ! 820 ! !! poorly sorted clay to silty sandstone. Includes meter-scale interbeds of ! ! ! ! ! !! Su ! Lake ! ! ! ! ! ! ! 980 Alderley 740 ! ! ! ! ! ! unconformable in the Baraboo Hills, 50 miles to the west (Stewart and ! 900 ! ! ! ! ! !!! ! !!! 900 ! !! º ! 16 ! ! !! !! ! « ! Su !! ! !!! ! ! ! ! ! ! !! !!! ! ! ! ! 780 ! ! ! !!!! 900 ! ! ! ! ! ! !!! green or red, silty clay and lesser moderately well-sorted sandstone with ! 820 ! ! ! ! ! ! ! ! 700 Os ! ! ! others, 2018; Stewart and Stewart, 2020). ! ! ! ! ! Om ! !!!! ! ! ! ! !! Ashippun ! !! ! !!!! ! ! ! ! ! ! 860 ! ! ! 820 interlaminated clay; common scour surfaces overlain by decimeter-scale, Maunesha R ! ! !! ! ! ! Davy Cr ! ! ! Os ! DG-1377 !! ! ! ! ! ! ! !! 780 ! ! !! Oa ! ! ! 740 ! Om References ! ! 36 DG-1378 ! Os 26 ! ! W !

massive to convolute-bedded silt or clay with white chert or angular chert 860 ! Ç 700 t « ! ! ! 780

(uncertain thickness—likely more than 800 ft) ! DG-1379 Yw ! Os ! ! ! ! 36 31 36

Waterloo Quartzite R17E ! 19 ° « ! ! ! R16E ! ! ! ! 36 31 36 Watertown ! ! ! 31 820 ! Buchholz, T.W., Falster, A.U., and Simmons, W.B., 2005, Mineralogy of pegmatites

! 820 ! R16E DG-1380 4444444444 Ç! ! ! R15E ! clasts; lesser centimeter-scale pebble-lag beds composed of quartzite and W ! 31 ! ! !!

31 R15E ! ! ! R14E ! Om !! 66 ! !! ! !! ! 820 4 !!! ! !!!!!! ! ! ! !!! ! ! _ !! 820 ! ! ! !! ! 820 Yw R14E 780 ! ! and spatially associated metasomatized zones, Michels Materials quarry, Pink, white, and gray pebble conglomerate to medium-grained quartzite R13E 740 ! DG-1409 ! ! ! ! Oa ! chert pebbles (millimeter scale) in a very coarse-grained sandstone matrix; Yw ! ! ! ! 6 000m ! ! 620 C’ 630 40 E WAUKESHA CO Waterloo, WI [abs.], in Easton, M., and Hollings, P., eds., Institute on Lake and green to gray schist. Observed minerals include quartz, muscovite, 610 JEFFERSON CO and lesser planar- to wavy-laminated silt and clay. Commonly intercalated 88°45' 88°37'30" 88°30' chlorite, kaolinite, plagioclase, andalusite, hematite, rutile, apatite, and 89°0' 88°52'30" Superior Geology, 51st annual meeting, Nipigon, Ontario, May 24–28, 2005, with centimeter- to decimeter-scale beds of medium- to coarse-grained, zircon (Geiger and others, 1982). Normally graded beds 5–15 ft thick com- Proceedings, Part 1—program and abstracts: Institute on Lake Superior well- to moderately well-sorted, crossbedded sandstone. Prevalent toward monly fine upward from granule conglomerate to fine-grained sandstone Geology, v. 65, p. 8–9. middle to base of St. Peter Formation, locally absent. Clayton, L., and Attig, J.W., 1990, Geology of Sauk County, Wisconsin: Wisconsin and siltstone. Pebbles (2–23 mm, long axis) of rounded quartzite and Geological and Natural History Survey Information Circular 67, 68 p., 2 plates, subrounded to subangular jasper and dark lithic fragments (probably slate) Prairie du Chien Group, undivided scale 1:100,000, https://wgnhs.wisc.edu/pubs/000317/. are concentrated near the base of beds. Sedimentary structures include (Lower Ordovician, Tremadocian to lower Floian; 0–140 ft) Geiger, C.A., Guidottie, C.V., and Petro, W.L., 1982, Some aspects of the petrologic trough crossbeds, low- and high-angle crossbeds, planar beds, and inter- and tectonic history of the Precambrian rocks of Waterloo, Wisconsin: Geo- Includes Shakopee and Oneota Formations. Uneroded thickness of about Opc nally structureless beds. Fine-grained (peliticand quartzose schist) intervals science Wisconsin, v. 6, p. 20–40, https://wgnhs.wisc.edu/pubs/gs06a03/. 150 ft. Overlies Trempealeau Group across a sharp contact. are typically 5–100 mm thick with common euhedral andalusite porphy- Mapping by E.K. Stewart, 2015–2019 Holm, D., Medaris, L.G., Jr., McDannell, K.T., Schneider, D.A., Schulz, K., Singer, B.S., Scale 1:100,000 Shakopee Formation (0–119 ft). Gray and beige dolostone grading into roblasts in a foliated, muscovite-chlorite groundmass. Lower contact with Geodatabase and cartography by K.C. Roushar and Jicha, B.R., 2020, Growth, overprinting, and stabilization of Proterozoic Map base from U.S. Geological Survey, The National Map digital data, 101 2345678910 lesser sandy dolostone. Interbedded (commonly across scour surfaces) underlying iron-formation is not directly observed in the map area. Detrital provinces in the southern Lake Superior region: Precambrian Research, v. US TOPO map series, 2016; and the Wisconsin Department of Natural Resources, 2016. KILOMETERS with centimeter- to decimeter-scale beds of very coarse-grained, well- zircons indicate a maximum depositional age of 1,643 Ga±11 Ma (Schwartz 339, 106687. 1012345 3°10´ Medaris, L.G., Jr., Malone, D.H., Hill, G.C., Singer, B.S., Jicha, B.R., Van Lankvelt, A., rounded sandstone; green to gray siltstone; or clay. Dolostone is massive, and others, 2018). Crops out or is shallowly buried near Waterloo. Shown in The map and cross sections are interpretations of the data available at the Contours represent the bedrock elevation surface, most of which is covered MILES Williams, M.L., and Reiners, P.W., 2019, The Wolf River orogeny: Geon 14 parallel laminated, oolitic, or vuggy. Vugs are millimeter to centimeter cross sections only. by up to 200 ft of unconsolidated material. The contour interval is 40 ft. time of preparation. Every reasonable effort has been made to ensure that this magmatism, sedimentation, and deformation in the southern Lake Superior scale and locally filled with quartz; some are clustered and appear to be Wisconsin Transverse Mercator projection, Roads and hydrography are shown for reference. APPROXIMATE MEAN interpretation conforms to sound scientific and cartographic principles; however, region [abs.], in Puumala, M., ed., Institute on Lake Superior Geology, 65th microbially derived (thrombolytic). Sandy dolostone is predominantly red Iron formation (uncertain thickness) DECLINATION, 2019 1991 Adjustment to the North American Datum of 1983 (NAD 83/91). the map should not be used to guide site-specific decisions without verification. annual meeting, Terrace Bay, Ontario, May 8–9, 2019, Proceedings, Part 1— with low-angle to planar-parallel crossbedding and scour surfaces; angular Blue-green, red, and white iron formation with varied clastic fraction. program and abstracts: Institute on Lake Superior Geology, v. 65, p. 64–65. XYi Proper use of the map is the sole responsibility of the user. dolostone clasts commonly overlie scour surfaces. Locally underlain by Includes interbedded and interlaminated carbonate, chert, and hema- Runkel, A.C., McKay, R.M., and Palmer, A.R., 1998, Origin of a classic cratonic sheet interbedded dolostone, sandstone, and clay of the Oneota Formation. tite-rich siltstone to mudstone; and thin beds (15–30 cm) of predominantly sandstone: Stratigraphy across the Sauk II-Sauk III boundary in the Upper Oneota Formation (0–36 ft). Gray to beige dolostone is massive to planar hematite-rich clay and silt or interlaminated, hematite-rich clay, silt, and Mississippi Valley: Geological Society of America Bulletin, v. 110, p. 188–210, to wavy-laminated, vuggy, and locally oolitic. Vugs are round, ovoid, or recrystallized carbonate. Primary mineral assemblage is iron- and mag- https://doi.org/b4wp8v. Schwartz, J.J., Stewart, E.K., and Medaris, L.G., Jr., 2018, Detrital zircons in the Wa- vertical; clustered in centimeter- to decimeter-thick intervals; and are likely nesium-rich silicates and lesser kaolinite, iron oxides, and chert; prevalent terloo Quartzite, Wisconsin: Implications for the ages of deposition and fold- microbially derived (thrombolytic). Includes lesser sandy dolostone and carbonate veins and detrital minerals present. Known from one drill core ing of supermature quartzites in the southern Lake Superior region [abs.], in interbedded sandstone. (WGNHS Slinger; WID: 14001388), several well construction reports, and Stewart, E.K., ed., Institute on Lake Superior Geology, 64th annual meeting, inferred from aeromagnetic anomalies. Lower contact is not directly May 15–18, 2018, Iron Mountain, Michigan, Proceedings, Part 1—program observed in the map area. Shown in cross section only. Cambrian and abstracts: Institute on Lake Superior Geology, v. 64, p. 93–94. Stewart, E.D., Stewart, E.K., Walker, A., and Zambito, J.J., IV, 2018, Revisiting the Trempealeau Group, undivided (Furongian; 0–100 ft) Interpretation Paleoproterozoic Baraboo interval in southern Wisconsin: Evidence for syn-depositional tectonism along the south-central margin of Laurentia: Includes Jordan and St. Lawrence Formations. For more information about the bedrock geology of Dodge County, Wisconsin, please _t refer to the supplemental report that accompanies this map. Precambrian Research, v. 314, p. 221–239. Jordan Formation (0–60 ft). White, beige, and yellow; medium- to coarse- A A’ Stewart, E.D., and Stewart, E.K., 2020, Geologic map of the 7.5-minute North grained; well-rounded; well-sorted sandstone; local green to gray, thin Freedom Quadrangle, Sauk County, Wisconsin: Wisconsin Geological and (centimeter scale) interbeds of clay or interlaminated fine-grained sand- Acknowledgments 1200 350 Natural History Survey Map 506, scale 1:24,000, https://wgnhs.wisc.edu/

TE754

SQ433 AZ437

SQ493

DG-1009 KT383 pubs/000973/.

SQ463 stone, silt, and clay. Poorly to moderately cemented. Includes common, This project benefited from the contributions of many collaborators. Amber Boudreau, GE457

Gill Creek

DG-37

DG-42

Lomira Creek Lomira

DG-1118

Lomira Creek Lomira

DG-92

localized high- and low-angle crossbeds and lesser gray, wavy siltstone Sarah Bremmer, Jackie DeBruyne, Ana Genthe, Greg Guenther, Lisa Haas, Mike Hurth, Kummel Creek

KS450 Su 300

TV522

Qu DG-51

EL709

IG300

1000 DG-1025

Alto Creek Matt Lamb, Pat McLaughlin, Mason Neuman, Drae Rogers, Alex Walker, and Jay KW313 laminae; localized metallic-gray sulfide mineralization (millimeter scale) DG-24 HMORICON ARSH

DG-53

Libby Creek

DG-34

Rock River

FL-369 disseminated in sandstone matrix. Thickness varies greatly across unit’s Zambito assisted with collecting drill core and processing samples. Pete Chase coor- RO703 SWTATE ILDLIFEA REA Os extent, but may reach 100 ft in northeastern Dodge County. dinated the collection of drill core and geophysical logs. Elizabeth Koozmin edited Qu Om 250 800 St. Lawrence Formation (0–66 ft). Consists of Lodi and Black Earth the map. I especially thank Bill Batten for his care and expertise running the drill rig. Opc Members. Members are present as laterally discontinuous interbedded Insightful discussions with Bill Batten, Eric Stewart, Tony Runkel, and Pat McLaughlin Oa 200 Os lithofacies. Overlies Tunnel City Group across a gradational contact. helped me improve the stratigraphic and structural interpretation of the map. Bill 600 Batten, Julia Steenberg, and John Craddock provided review comments that improved Opc 150 —Lodi Member (0–63 ft). Red, green, and beige; fine- to medium-grained; the quality of the map. Finally, thank you to the landowners who allowed access to

poorly sorted; glauconitic; mottled; dolomitic sandstone and silty sand- 400 level) sea (above ers their property to extract bedrock drill core and examine rock outcrops. c Oa stone. Sandstone beds are very poorly sorted with a predominant mottled g 100 This geologic map was funded in part by the USGS National Cooperative Geologic texture of probable microbial origin; local coarse-grained, glauconitic Oa (15–20 percent), centimeter-scale crossbed sets overlie scour surfaces. Mapping Program under StateMap award numbers G15AC00161, G16AC00143, 200 g ? c 50 Includes common centimeter-scale interbeds of planar-laminated, fine- G17AC00138, and G18AC00156. The views and conclusions contained in this docu- ment are those of the authors and should not be interpreted as necessarily represent- w Kenneth R. Bradbury, Director and State Geologist

grained sandstone and siltstone to mudstone with Skolithos burrow or Elevation in met ing the official policies, either expressed or implied, of the U.S. Government. feetElevation in (above sea level) 0 ? 0 3817 Mineral Point Road, Madison, WI 53705 • 608/262.1705 • WGNHS.org soft-sediment deformation including flame structures and millimeter-scale, Ypm lithified dolomite clasts. Gradational contact and locally interbedded with XYb XYb bedding ? -50 underlying Black Earth Member. -200 Ypm XYi An EEO/AA employer, University of Wisconsin–Madison provides equal Ypm Yw —Black Earth Member (0–13 ft). Tan, pink, or gray; mottled; fine-grained; Ypm XYi XYb Ypm opportunities in employment and programming, including Title VI, Title IX, silty dolostone. Exhibits wispy, discontinuous, gray, fine-grained lami- West East and the Americans with Disabilities Act (ADA) requirements. nations; and millimeter-scale, calcite-filled vugs of probable microbial (stromatolitic) origin.

B bend B’ C C’

1200 1200 350 350 TMHERESA ARSH SWTATE ILDLIFE HMORICONARSH AREA

sh River

DG-1009 XG858

DG-1399

DG-15 NWATIONAL ILDLIFEA REA DG-46 300 300

DG-136 DG-12 1000

KM694

Rock River 1000 Mill Creek

Rock River

DG-1132

DG-1384

Rock River

Rock River

Rock River

Mill Creek

DG-39

RJ807

TT893

Cambra Creek Cambra

Cambra Creek Cambra

RW401 Su CO-38 MLUD AKE

AH348

OH482

ME872

MW899

Cr

HD610 Su NQ391

DG-1389

DG-59

Su RX722

FY130

ON374

JE-854 DG-447 TATE ILDLIFE REA

JE-3 SW A JE-4

Os MY146 Opc Opc KM212 Rock River Os Qu 250 Opc 250 Qu Oa Opc Oa el) 800 Oa Oa Os 800 Opc Om Qu Opc

el)

vel) 200 c Oa 200 600 c 600 Opc Oa w 150 150 Xw w w c g 400 ers (above sea lev 400 100 g 100 eet (above sea lev e bedding ? w c 200 200 50 50 ? Ypm bedding Ypm

Elevation in feetElevation in (above sea le

Elevation in meters (aboveElevation in meters sea level)

Elevation in f Elevation in 0 0 Elevation in met 0 0 XYb XYb Xw bedding Yw XYb XYi bedding XYi Ypm bedding XYi Ypm Ypm Ypm Ypm Ypm -50 –50 -200 –200 West East West East bend Vertical exaggeration of cross sections is 20x