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 497.0 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 <1630 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 ! ! ! !