ILLINOIS AQUIFER, STRATIGRAPHIC, AND LITHOLOGIC CODES

CENOZOIC

CENOZOIC……………………………………………………………….. ……... 100CEZC
CENOZOIC ERATHEM………………………………………………………….. 100CNZC

QUATERNARY

CLAY – HOLOCENE AND PLEISTOCENE SERIES………………………... 110CLAY
GRAVEL – HOLOCENE AND PLEISTOCENE SERIES…………………….. 110GRVL
GRAVEL AND CLAY – HOLOCENE AND PLEISTOCENE SERIES………. 110GVCL
HARDPAN – HOLOCENE AND PLEISTOCENE SERIES………………….. 110HRDP
MARL - HOLOCENE AND PLEISTOCENE SERIES………………………… 110MARL
PEAT - HOLOCENE AND PLEISTOCENE SERIES………………………… 110PEAT
QUATERNARY SYSTEM……………………………………………………….. 110QRNR
SAND - HOLOCENE AND PLEISTOCENE SERIES………………………… 110SAND
SAND AND CLAY - HOLOCENE AND PLEISTOCENE SERIES………….. 110SDCL
SAND AND GRAVEL - HOLOCENE AND PLEISTOCENE SERIES………. 110SDGV
SAND, GRAVEL, AND CLAY - HOLOCENE AND PLEISTOCENE SERIES 110SGVC
SILT - HOLOCENE AND PLEISTOCENE SERIES………………………….. 110SILT

HOLOCENE

ALLUVIUM………………………………………………………………………… 111ALVM
FILL………………………………………………………………………………… 111FILL
HOLOCENE SERIES……………………………………………………………. 111HLCN
SOIL……………………………………………………………………………….. 111SOIL

PLEISTOCENE

PLEISTOCENE SERIES………………………………………………………… 112PLSC
TILL – PLEISTOCENE SERIES………………………………………………... 112TILL

PALEOZOIC

PALEOZOIC ERATHEM………………………………………………………… 300PLZC

PENNSYLVANIAN

PENNSYLVANIAN……………………………………………………………….. 320PELV
PENNSYLVANIAN SYSTEM……………………………………………………. 320PSLV


VIRGILIAN

MCLEANSBORO GROUP………………………………………………………. 322MCLB
MATTOON FORMATION OF MCLEANSBORO GROUP……………………. 322MTTN
VIRGILIAN, MISSOURIAN, DESMOINESIAN SERIES………………………. 322VGMD

MISSOURIAN

BOND FORMATION OF MCLEANSBORO GROUP…………………………. 323BOND
MODESTO FORMATION OF MCLEANSBORO GROUP…………………… 323MDST

DESMOINESIAN

CARBONDALE FORMATION OF KEWANEE GROUP……………………… 325CBDL
DESMOINESIAN SERIES………………………………………………………. 325DSMS
KEWANEE GROUP……………………………………………………………… 325KEWN
SPOON FORMATION OF KEWANEE GROUP……………………………… 325SPON

ATOKAN

ABBOTT FORMATION OF MCCORMICK GROUP………………………….. 326ABBT
ATOKAN SERIES………………………………………………………………… 326ATOK
MCCORMICK GROUP…………………………………………………………… 326MCMK

MORROWAN

CASEYVILLE FORMATION OF MCCORMICK GROUP…………………….. 328CSVL
MORROWAN SERIES…………………………………………………………… 328MRWN

MISSISSIPPIAN

MISSISSIPPIAN…………………………………………………………………… 330MISP
MISSISSIPPIAN SYSTEM………………………………………………………. 330MSSP

CHESTERIAN

CEDAR BLUFF GROUP………………………………………………………… 332CDBL
CHESTERIAN SERIES………………………………………………………….. 332CSTR
DOWNEYS BLUFF LIMESTONE OF CEDAR BLUFF GROUP…………….. 332DBLF
GOLCONDA GROUP……………………………………………………………. 332GLCD
OKAW GROUP…………………………………………………………………… 332OKAW
PAINT CREEK GROUP…………………………………………………………. 332PCRK
RENAULT LIMESTONE OF CEDAR BLUFF GROUP………………………. 332RNLT
WEST BADEN GROUP…………………………………………………………. 332WSDB
YANKEETOWN SANDSTONE OF CEDAR BLUFF GROUP……………….. 332YNKN

MERAMECIAN

AUX VASES SANDSTONE……………………………………………………… 333AXVS
BORDEN SILTSTONE…………………………………………………………… 333BRDN
BURLINGTON LIMESTONE……………………………………………………. 333BRLG
FERN GLEN FORMATION……………………………………………………… 333FRGL
FORT PAYNE FORMATION……………………………………………………. 333FRPN
KEOKUK-BURLINGTON LIMESTONE………………………………………… 333KKKB
KEOKUK LIMESTONE………………………………………………………….. 333KKUK
MEPPEN FORMATION…………………………………………………………. 333MPPN
ST. GENEVIEVE LIMESTONE……………………………………………….. 333SGVV
SALEM LIMESTONE……………………………………………………………. 333SLEM
SONORA FORMATION…………………………………………………………. 333SNOR
SPRINGVILLE SHALE…………………………………………………………... 333SPGV
ST. LOUIS LIMESTONE…………………………………………………………. 333STLS
ULLIN LIMESTONE……………………………………………………………… 333ULIN
VALMEYERAN SERIES………………………………………………………… 333VLMR
WARSAW SHALE……………………………………………………………….. 333WRSW

KINDERHOOKIAN.

CHOUTEAU LIMESTONE………………………………………………………. 339CHUT
“GLEN PARK” FORMATION OF NEW ALBANY GROUP…………………... 339GLPK
HANNIBAL SHALE OF NEWALBANY GROUP………………………………. 339HNBL
KINDERHOOKIAN SERIES…………………………………………………….. 339KDRK
MCCRANEY LIMESTONE OF NORTH HILL GROUP………………………. 339MCCR
NEW ALBANY GROUP…………………………………………………………. 339NALB
NORTH HILL GROUP…………………………………………………………… 339NTHL
PROSRECT HILL SILTSTONE OF NORTH HILL GROUP…………………. 339PPCH
STARRS CAVE LIMESTONE OF NORTH HILL GROUP…………………… 339SRCV

DEVONIAN

DEVONIAN……………………………………………………………………….. 340DEVN
DEVONIAN SYSTEM……………………………………………………………. 340DVNN
DEVONIAN-SILURIAN SYSTEM………………………………………………. 340DVSL

UPPER DEVONIAN

UPPER DEVONIAN SERIES…………………………………………………… 341DVNNU
GRASSY CREEK SHALE OF NEW ALBANY GROUP……………………… 341GRCK
LOUISIANA LIMESTONE OF NEW ALBANY GROUP……………………… 341LUSN
NEW ALBANY GROUP…………………………………………………………. 341NALB
SWEETLAND CREEK SHALE OF NEW ALBANY GROUP………………… 341SDCK
SYLAMORE SANDSTONE OF NEW ALBANY GROUP……………………. 341SLMR
SAVERTON SHALE OF NEW ALBANY GROUP……………………………. 341SVRN

MIDDLE DEVONIAN

CEDAR VALLEY LIMESTONE…………………………………………………. 344CDVL
MIDDLE DEVONIAN SERIES OF NEW ALBANY GROUP…………………. 344DVNNM
HUNTON MEGAGROUP………………………………………………………… 344HNTN
WAPSIPINICON LIMESTONE………………………………………………….. 344WPPC

LOWER DEVONIAN

BACKBONE LIMESTONE……………………………………………………… . 347BCKB
BAILEY LIMESTONE…………………………………………………………….. 347BILY
CLEAR CREEK CHERT…………………………………………………………. 347CLCK
LOWER DEVONIAN SERIES…………………………………………………… 347DVNNL
GRASSY KNOB CHERT………………………………………………………… 347GRKB

SILURIAN

SILURIAN DOLOMITE…………………………………………………………… 350SIDO
SILURIAN SYSTEM……………………………………………………………… 350SLRN

NIAGARAN

JOLIET FORMATION……………………………………………………………. 355JOLT
MOCCASIN SPRINGS FORMATION………………………………………….. 355MNSP
NIAGARAN SERIES……………………………………………………………… 355NIGR
RACINE FORMATION…………………………………………………………… 355RCIN

ALEXANDRIAN

ALEXANDRIAN SERIES………………………………………………………… 358ALXD
EDGEWOOD LIMESTONE……………………………………………………… 358EDGD
KANKAKEE FORMATION………………………………………………………. 358KNKK

ORDOVICIAN

ORDOVICIAN SYSTEM…………………………………………………………. 360ODVC


CINCINNATIAN

BRAINERD SHALE OF MAQUOKETA………………………………………… 362BRRD
CAPE LIMESTONE………………………………………………………………. 362CAPE
CLERMONT SHALE MEMBER OF SCALES SHALE……………………….. 362CLRM
CINCINNATIAN SERIES………………………………………………………… 362CNCN
ELGIN SHALE MEMBER OF SCALES SHALE………………………………. 362ELGN
FORT ATKINSON FORMATION OF MAQUOKETA…………………………. 362FRAK
MAQUOKETA SHALE…………………………………………………………… 362MQKS 
MAQUOKETA GROUP………………………………………………………….. 362MQKT
NEDA FORMATION OF MAQUOKETA GROUP…………………………….. 362NEDA
ORCHARD CREEK SHALE MEMBER OF SCALES SHALE………………. 362OCCK
SCALES SHALE OF MAQUOKETA GROUP………………………………… 362SCLS
THEBES SANDSTONE MEMBER OF SCALES SHALE……………………. 362THBS

CHAMPLAINIAN

ANCELL…………………………………………………………………………… 365ANCE
ANCELL GROUP………………………………………………………………… 365ANCL
CHAMPLAINIAN SERIES………………………………………………………. 365CMPL
DECORAH SUBGROUP OF GALENA GROUP……………………………… 365DCRH
DUNLEITH FORMATION OF KIMMSWICK GROUP………………………… 365DNLT
DUTCHTOWN LIMESTONE OF ANCELL GROUP………………………….. 365DTCN
DUBUQUE FORMATION OF KIMMSWICK SUBGROUP…………………… 365DUBQ
EVERTON DOLOMITE………………………………………………………….. 365EVRN
GUTTENBERG FORMATION OF DECORAH SUBGROUP………………… 365GBRG
GRAND DETOUR FORMATION OF PLATTIN SUBGROUP……………….. 365GDDR
GALENA GROUP………………………………………………………………… 365GLEN
GLENWOOD FORMATION OF ANCELL GROUP…………………………… 365GLND
GALENA-PLATTEVILLE………………………………………………………… 365GLPV
JOACHIM DOLOMITE OF ANCELL GROUP………………………………… 365JCHM
KINGS LAKE FORMATION OF DECORAH SUBGROUP…………………… 365KGLK
KIMMSWICK SUBGROUP OF GALENA GROUP…………………………… 365KMCK
MIFFLIN FORMATION OF PLATTIN SUBGROUP………………………….. 365MFLN
NACHUSA FORMATION OF PLATTIN SUBGROUP………………………… 365NCHS
PECATONICA FORMATION OF PLATTEVILLE GROUP…………………… 365PCNC
PLATTIN SUBGROUP OF PLATTEVILLE GROUP………………………….. 365PLTN
PLATTEVILLE GROUP………………………………………………………….. 365PLVL
PRAIRIE DU CHIEN GROUP…………………………………………………… 365PRDC
QUIMBYS MILL FORMATION OF PLATTIN SUBGROUP………………….. 365QMBM
SPECHTS FERRY FORMATION OF DECORAH SUBGROUP……………. 365SPCT
ST. PETER SANDSTONE OF ANCELL GROUP…………………………….. 365STPR
WISE LAKE FORMATION OF KIMMSWICK SUBGROUP………………….. 365WSLK

ORDOVICIAN-CAMBRIAN SYSTEM………………………………………….. 367OVCB

CANADIAN

CANADIAN SERIES……………………………………………………………... 368CNDN
COTTER-JEFFERSON CITY DOLOMITES…………………………………… 368CRJF
COTTER DOLOMITE……………………………………………………………. 368CTTR
GUNTER SANDSTONE OF PRAIRIE DU CHIEN GROUP…………………. 368GNTR
JEFFERSON CITY DOLOMITE………………………………………………… 368JFRC
NEW RICHMOND SANDSTONE OF PRAIRIE DU CHIEN GROUP………. 368NRCM
ONEOTA DOLOMITE OF PRAIRIE DU CHIEN GROUP……………………. 368ONOT
PRAIRIE DU CHIEN……………………………………………………………… 368PRAD
POWELL DOLOMITE……………………………………………………………. 368PWLL
ROUBIDOUX FORMATION…………………………………………………….. 368RBDX
SHAKOPEE DOLOMITE OF PRAIRIE DU CHIEN GROUP………………… 368SHKP
SMITHVILLE FORMATION……………………………………………………… 368SMVL
SMITHVILLE-POWELL FORMATIONS………………………………………... 368SMVP

CAMBRIAN

CAMBRIAN SYSTEM……………………………………………………………. 370CMBR

ST. CROIXIAN

DERBY-DOERUN MEMBER OF FRANCONIA FORMATION……………… 372DRBD
DAVIS MEMBER OF FRANCONIA FORMATION…………………………… 372DVIS
EAU CLAIRE FORMATION…………………………………………………….. 372ECLR 
ELMHURST SANDSTONE MEMBER OF EAU CLAIRE FORMATION…… 372ELMR
ELMHURST-MT. SIMON……………………………………………………….. 372ELMS
EMIENCE-POTOSI FORMATIONS……………………………………………. 372EMCP
EMINENCE FORMATION………………………………………………………. 372EMNC 
EMINENCE-POTOSI…………………………………………………………….. 372EMPT
FRANCONIA……………………………………………………………………… 372FRAN
FRANCONIA FORMATION……………………………………………………... 372FRNC
GALESVILLE SANDSTONE……………………………………………………. 372GLVL
IRONTON-GALESVILLE………………………………………………………… 372IRGL
IRONTON SANDSTONE………………………………………………………... 372IRNN
JORDAN SANDSTONE…………………………………………………………. 372JRDN
LOMBARD DOLOMITE MEMBER OF EAU CLAIRE FORMATION……….. 372LMBD
MOMENCE SANDSTONE MEMBER OF EMINENCE FORMATION……… 372MMNC
MOUNT SIMON SANDSTONE………………………………………………… 372MNSN
POTOSI FORMATION…………………………………………………………… 372POTS
PROVISO SILTSTONE MEMBER OF EAUCLAIRE FORMATION………… 372PRVS
CROIXAN SERIES………………………………………………………………. 372SCRX



PRECAMBRIAN

BASEMENT COMPLEX…………………………………………………… ……. 400BCPX
PRECAMBRIAN ERATHEM…………………………………………………….. 400PCMB 
BASEMENT……………………………………………………………………….. BASEMENT

OTHER

BEDROCK…………………………………………………………………………. BEDROCK