U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP I-2533 U.S. GEOLOGICAL SURVEY

BEDROCK GEOLOGIC MAP OF THE ST. LOUIS 30' x 60' QUADRANGLE, AND ILLINOIS

Compiled by Richard W. Harrison

INTRODUCTION The most conspicuous magnetic features on the map on sheet 2 are two pronounced anomalies, a roughly circular magnetic high in This map is a compilation of the bedrock geology of the St. Louis the northwest comer of the quadrangle (Wentzville anomaly) and 30' x 60' quadrangle (1:100,000 scale). It presents a generalized a 40.4-mile-long northeast-trending magnetic high through the overview of the distribution of formations, stratigraphy, and struc­ center of the quadrangle (St. Charles anomaly). Both magnetic ture found in the area. With the exception of structural and tectonic anomalies have corresponding positive gravity anomalies (Mateker interpretations made by the author, it is entirely derived from and others, 1966; Phelan, 1969). The Wentzville anomaly was pre-existing data. Geologic maps used in compilation were from drilled by the National Lead Company in the 1950's. The drill hole the archives of the Missouri Department of Natural Resources, bottomed deep in the Middle basement, which was Rolla, Mo., and from publications of the Illinois State Geological found to consist dominantly of gabbro, norite, and diorite, intruded Survey, Champaign, Ill. The index map (sheet 1) shows the map by granitic dikes. Analyses of the geophysical data defining the area of the data sources that are listed in Appendix A of this Wentzville anomaly by Mateker and others (1966) and Phelan pamphlet. Subsurface data used to construct cross sections came (1969) indicate that this mafic material extends to a depth of as from the same sources. There are some minor inconsistencies much as 8,000 ft. They proposed a similar cause for the St. Charles between the map and cross sections that are unresolved. Descrip­ anomaly and suggested that it defines a buried Middle Proterozoic tions of units were taken from the legends of maps used for graben. Anderson (1988) and Sims and others (1987) suggested compilation and from Howe and Koenig (1961), Willman and that the St. Charles anomaly lies along a segment of an ancient others (1975), and Thompson (1986, 1991). Previous investiga­ suture zone. Six of the eight minor earthquakes recorded since tions that have dealt primarily with the St. Louis area include: 1974 in the St. Louis area could reasonably be related to the St. Engelmann (1847), Keyes (1898), Fenneman (1911), Hinchey Charles anomaly; Mateker and others (1966) also related minor and others (1947), Willman and Frye (1958), and Martin and Wells earthquake activity to the St. Charles anomaly. (1966). Bedrock is poorly exposed throughout the extensively urbanized St. Loui~ quadrangle. In addition, much of the area is covered by loess, glacial till, residuum, and fluvial deposits Table 1.-Recorded seismic events in the area of the St. Louis (Schultz, 1993). Best exposures of bedrock are in river bluffs, road 30' x 60' quadrangle since 1974. Locations are plotted on the cuts, and quarries. map on sheet 2. [From the files of the Department of Earth and Atmospheric Sciences, St. Louis University] MAGNETIC ANOMALIES AND SEISMICITY Longitude Latitude Magnitude Aeromagnetic data were used to investigate the Middle Proter­ Date ozoic basement of the St. Louis area. The map on sheet 2 is a (W) (N) (mq) regional magnetic anomaly map of the St. Louis quadrangle 1) 09/27n4 90.56 38.70 1.5 adapted from Zietz and others (1984) and Heigold (1976). Mag­ 2) 09/27n4 90.54 38.71 1.6 netic anomalies probably reflect structures and(or) lithologic vari­ 3) 11/30n4 90.35 38.85 1.5 ations in the Middle Proterozoic basement buried beneath Paleo­ 4) 12/18n4 90.90 38.60 1.6 5) o912on8 90.28 38.57 3.1 zoic strata. Also shown on this map are major structures in 6) o6to3n9 90.53 38.61 2.1 rocks, pinch-out lines. related to major unconformities, 7) 12/01/80 90.85 38.72 2.4 and the locations of recent earthquake epicenters. The earth­ 8) 12/26/91 90.05 38.84 2.4 quakes were minor, having body wave magnitudes rangin~ from 1.5 to 3.1. Their epicenters have an accuracy radius of approxi­ mately 6.2 mi (R.B. Herrmann, St. Louis University, oral com­ STRUCTURE mun., 1992). Table 1 is a summary of recorded seismicity in the St. Louis 30' x 60' quadrangle since 1974. The St. Louis quadrangle is located between the Ozark Moun­ tain uplift to the south and the Illinois basin to the north and east. Overall, bedding dips very gently to the northeast at about 55 ft/mile or less than 1 degree across the quadrangle. These gentle dips are interrupted by several narrow zones of deformation. In Manuscript approved for publication December 9, 1994. some of these zones, deformation is very intense. Due to extensive cover by Quaternary surficial deposits, a deep zontal stratigraphic contacts; such features do not provide ade­ weathering profile, and widespread urban and suburban develop­ quate piercing points needed to document strike-slip offsets. Large ment, exposures of geologic structures in the St. Louis area are apparent lateral offsets of subhorizontal planes can be produced by limited. The general absence of structural data on existing maps for relatively minor vertical uplift and subsequent erosion. this area reflects these· problems. Subsurface data such as drill records and geophysical surveys are the best information available Valmeyer Anticline, O'Fallon Fault for evaluating the structural geology of this region. Paralleling the Eureka-House Springs structure and approxi­ The major structural features of the St. Louis area are plotted on mately 12 mi to the northeast is the Valmeyer anticline. In Missouri, the regional· magnetic anomaly map (sheet 2). Also shown are this structure is poorly exposed, but it has moderate subsurface pinch-out lines for and Devonian strata and the expression with as much as 100ft of structural relief, down to the Maquoketa Shale. These pinch-outs are the results of regional southwest (see cross section B-B'). Where it is better exposed near uplift (principally of the Ozark area) and the subsequent develop­ the town of Valmeyer, Ill., it is an asymmetric, monoclinal fold that ment of unconformities. has a steep southwest limb. The youngest known formation Few of the structures that cut Paleozoic rocks are along the involved in the folding is the St. Louis Limestone northeast-trending grain of the Middle Proterozoic basement as (Odom and others, 1961). defined by the magnetic anomaly map. Rather, they strike north­ A possible northwest structural extension of the Valmeyer west, north-northwest, north-northeast, and west-northwest. Most anticline is the O'Fallon fault. This fault is shown on the geologic of these structures are asymmetric folds and related faults. All of the map of St. Charles County by Missouri Geological Survey (1975), structures in the St. Louis quadrangle except the ·Eureka-House and on the geologic map of Missouri (Anderson, 1979). It was Springs structure are down to the southwest or west, toward the mapped as a down-to-the-southwest fault that juxtaposes the Ozark uphft and away from the Illinois basin. Mississippian Salem Formation against the Burlington and Keokuk Limestones. Eureka-House Springs Structure Cap au Gres-Waterloo-Dupo Structure The Eureka-House Springs structure is the westernmost zone of deformation in the St. Louis quadrangle. This northwest-striking The major structural feature affecting Paleozoic rocks in the St. structure is extremely complex. Engel (1939) and McCracken Louis area is a complex monoclinal fold (or drape fold) and (1966, 1971) described the structure as an anticline that plunges associated faults. This structure occurs in the northern part of the both to the southeast and northwest having a crest near House quadrangle on an east-southeast trend (Cap au Gres structure) and Springs, Mo. Tikrity (1968) referred to the structure as an asym­ then curves to a south-southeast trend (Florissant dome and metric anticlinal fold having associated faults that resulted in as Waterloo-Dupo anticline; see map on sheet 2). The steep limb of much as 425 ft of structural relief, down to the southwest. this drape fold faces the southwest and has 600-1,000 ft of Clendenin and others (1993) described it as consisting of three structural relief. Characteristically, the structure consists of alternat­ right-stepping en echelon fault segments, each approximately ing elongated domes and saddles. Where exposed, several sym­ 9.3-15.5 mi in length, and each having a relatively independent pathetic faults are recognized, but by far, most of the structural tectonic history. They suggested that a minimum of 6.2 mi of relief is accommodated by folding (Rubey, 1952). Companion left-lateral strike-slip motion has occurred on the structure. asymmetrical synclines (Troy-Brussels, Cheltenham, and Colum­ Where the Eureka-House Springs structure crosses the St. Louis bia synclines) parallel the drape fold to the southwest. quadrangle, it is a narrow fault zone that has minor down-to-the­ Previous workers (Rubey, 1952; Cole, 1961; Tikrity, 1968; northeast stratigraphic offset (see cross sections B-B' and C-C' McCracken, 1971) considered the Cap au Gres structure and (sheet 2) and Whitfield, 1989). It is a very poorly defined structure Waterloo-Dupo anticline (including the Aorissant dome) to be and has been mapped over only short intervals. separate structural features and called upon compressional, strike­ Clendenin and others (1993) have identified Middle and Late slip, or extensional tectonics to explain them. However, in order to Ordovician, Middle Devonian, and post-Mississippian movement maintain consistent and balanced structural offset, these structures on the Eureka-House Springs structure. Tikrity (1968) reported are interpreted as parts of a single system. Furthermore, these approximately 50 ft of Devonian uplift on this structure. Cross structures remarkably resemble monoclinal drape folds found on section C-C' reveals probable Early Mississippian uplift [Fern Glen the Colorado Plateau that formed in sedimentary strata overlying Formation (lowest part of Mkbf) rests directly on Bushberg Sand­ reactivated basement faults (Kelley, 1955; Davis, 1978). Davis stone (Mb), and the Chouteau Limestone (Me) is absent]. The (1978) experimentally produced drape folds identical to the Cap Burlington and Keokuk Limestones are the youngest rocks au Gres-Waterloo-Dupo structure, including its sharp bends, by deformed by this structure, indicating a post-Osagean movement. subjecting buried, near-vertical structures to compression. A similar The Eureka-House Springs structure abruptly truncates the origin is suggested for the Cap au Gres-Waterloo-Dupo structure. southwestern end of the St. Charles magnetic anomaly (see map Characteristic of drape folds are zones of layer-parallel shorten­ on sheet 2) and closely follows the northeast Missouri tectonic zone ing or shear (Brown, 1988; Reches.and Johnson, 1978; Friedman of Kisvarsanyi (1974, 1984). These relations strongly suggest that and others, 1976). Suc.h zones are exposed in the Alton Bluffs area the structure has a ancestry and was reactivated at (Collinson and others, 1979; Thompson, 1986), in the Alton Stone various times during the Paleozoic. During the Precambrian, it Company quarry (NE1f4 sec. 11, T. 5 N., R. 7 E.; see Alton 7.5- could have accommodated several miles of offset. However, based minute quadrangle), and in the Fort Bellefontaine quarries (sec. 4, on the lack of through-going, continuous deformation in Paleozoic T. 4 N., R. 7 E.; see Columbia Bottom 7.5-minute quadrangle). In rocks, it seems unlikely that the Eureka-House Springs structure all of these areas, shortening and shearing occurs in the Mississip­ could have had more than a few hundred feet of offset since the pian St. Louis Limestone. Figure 1 diagrammatically illustrates the Precambrian. The 6.2 mi of strike-slip movement suggested by occurrence in the Alton Stone Company quarry. Its principal Clendenin and others (1993) was based on the offset of subhori- features consist of horizontal detachment surfaces connected by

2 continued minor uplift during Early Mississippian (Kinderhookian) time. Tikrity (1968) thought that the Late Devonian deformation was down to the northeast on this structure, an interpretation reiterated ~ ~ ~ ~ Asymmetrical contact ~ t. ~ ~ by Nelson and Lumm (1985). However, their inconclusive data ~~~~Al>.A A~AA~AAt.At.AAAA ~ A~ A A A .o.2-12ft.brecciatedzoneA A A A ~ t. A was based on widespread unconformities, and, in fact, was prob­ A A .6. A A A A A A A A A ~ A A A A A ~ A t. ably more related to regional uplift in the Ozark area than to local AAAAAAAAt:. t:.t...Atit:. t.At...t.t.t:.A structure. The detailed work of Rubey (1952) indicated that Late . ·~:__._~; ~or~ta~achr·;~t~· r·. Devonian uplift on the Cap au Gres segment was down to the southwest, sympathetic to later deformation. I I I 1=1=1 I /t J? I I It has long been recognized that most of the deformation on the Tectonic slickolites Cap au Gres structure is constrained as post-St. Louis Limestone (Mississippian, Meramecian) and pre-Tradewater (Pottsville) For­ 0 10 FEET mation (, Morrowan) (Weller, 1907; Rubey, 1952), Approximate scale and on the Waterloo-Dupo anticline as post-Renault Limestone (Mississippian, Meramecian and Chesterian) and pre-Tradewater Figure 1. Diagrammatic sketch of a zone of layer-parallel (Pottsville) Formation (Weller, 1939) to pre-Desmoinesian (Cote shearing and shortening in the Alton Stone Company quarry, and others, 1970; Nelson and Lumm, 1985). These relatively tight Alton, Ill. constraints place the principal deformation as occurring near the Mississippian-Pennsylvanian boundary. Different elevations for the base of Pennsylvanian strata across low-angle thrusts and overlain by a breccia zone from 2 to 12 ft the Cap au Gres structure indicate as much as 200 ft of post­ thick. The breccia zone contains subangular to subrounded frag­ depositional uplift (Rubey, 1952). Post-Pennsylvanian uplift has ments of limestone in a matrix of green gouge (?)and (or) shale. also been described on the Waterloo-Dupo segment by Nelson Many fragments have striated margins. The upper contact of the and Lumm (1985). Difficulties arise in placing further time con­ breccia zone with bedded limestone is irregular and asymmetrical, straints on these post-Pennsylvanian movements because of the having steep faces toward the northeast. The breccia zone origi­ absence of Permian and strata, and the paucity of nally was an intraformational, sedimentary breccia horizon, which formations in the area. Rubey (1952) interpreted as localized subsequent deformation. Thrust faults verge upward much as 175 ft of late Tertiary uplift on the Cap au Gres structure based on apparent displacements of an erosional surface overlain toward the northeast and are mineralized with fibrous calcite whose by the Grover Gravel. However, uncertainties in the reliability of growth pattern indicates thrust motion. Slickenside striations with a correlating individual surfaces and the fact that deposits of Grover N. 50°--60° E. trend occur on the detachment surfaces. In the Gravel occur at various elevations in the area make these timing bedded limestone beneath the detachment surface, vertical tee:.. constraints tentative. Perhaps Rubey's strongest argument for late tonic slickolites strike N. 20°--40° W. All of these features are Tertiary tectonism in the area is the northeastward tilting of Grover consistent with northeast-southwest-directed compression, which is Gravel deposits in St. Louis County, opposite to the direction of also inter-Waterloo-Dupo structure. their cross bedding. Contrary to the ideas of Tikrity (1968), there is no evidence to support Ordovician deformation along this structure. Tikrity (1968) St. Louis Fault Zone i11terpreted a thinning of the Ordovician Maquoketa Shale along the flanks of the. florissant dome as syndepositional deformation. The St. Louis fault zone is a north-northeast-trending structure in However, this unit is not thinned over the crest of the dome as it the eastern part of the St. Louis quadrangle (see map on sheet 2). should be in syndepositional deformation. An alternative interpre­ It was first described by Frank (1948), who noted the apparent tation is post-depositional, tectonic thinning related to lithologic control of the fault zone on the course of the Mississippi River as it competence. Tectonic thinning is necessary in drape folding to cuts across the flank of the structurally and topographically high accommodate changes in bed length (Brown, 1988). Ozark uplift instead of flowing around it and into the low areas to Tikrity (1968) also misinterpreted the increase in thickness of the the east. The St. Louis fault zone is ~m on-strike projection of the Maquoketa Shale from the crest of the florissant dome eastward as Roselle lineament of Gillerman (1970). syndepositional. Cross sections A-A', B-B', and C-C' show that Most of this structure lies beneath the Mississippi River, but well this thinning is controlled by a regional unconformity that also data indicates as much as 150 ft of down-to-the-west displacement systematically affects Silurian strata as well as the Ordovician in the southern part of the quadrangle, which apparently dissipates Kimmswick Limestone. Since Late Devonian rocks directly overlie northward (see cross sections A-A', B-B', and E-E'). Exposures the unconformity, a regional tilting away from the Ozark uplift in old quarries (now filled) along South Broadway in downtown St. during post-Silurian, pre-Late Devonian time is a more likely Louis showed this structure to be a zone several hundred feet wide interpretation. consisting of multiple, vertical surfaces (Brill and others, 1960). Initial deformation along the Cap au Gres-Waterloo-Dupo Some of the fault surfaces were mineralized with sphalerite, and structure appears to have begun in Late Devonian or Early some showed dip-slip, down-to-the-east displacement. Two small Mississippian time, contemporaneous with continued regional tilt­ earthquakes· (3.1 and 2.4 mq) recorded since 1974 were probably ing away from the Ozark uplift (Rubey, 1952). Rubey (1952) cited along the St. Louis fault zone. stratigraphic evidence for approximately 40 ft of Late Devonian Although inconclusive, the St. Louis fault zone does have some uplift; Rubey (1952), Weller (1906), and Branson (1918) characteristics of a strike-slip structure, particularly the multiple, described stratigraphic thinning and faunal changes indicative of vertical strands having opposing throw. In addition, as depicted on

3 Analysis of mineral growth consistently indicates that the N. EXPlANATION 45°-70° E. faults have moved in a left-lateral sense and the N. Vertical joint 5°-10° E. faults in a right-lateral sense. Cross sections through the N 5°-10° E. fault set provided by the bluffs suggest positive flower Strike-slip fault-Arrows show relative movement structures, indicating transpression. The amount of displacement on any of the faults is unknown. Reconnaissance of the Alton Stone Company quarry, approximately 1 mi northeast of the Alton Bluffs, discovered additional left-lateral strike-slip faults that strike N. 45°-70° E. At the mouth of Deer Lick Hollow (SW 1/4 SE 1/4 sec. 11 and N 1/2 NEl/4 sec. 14, T. 6 N., R. 13 W.; see Brussels 7.5-minute quad­ rangle), Rubey (1952) described a right-lateral strike-slip fault zone that strikes between N. 25° E. and N. 35° E. He stated that the Cap au Gres structure is offset more than 300 ft horizontally, and indicated that the strike-slip faults show a strong component of transpression. The only constraints on the age of these rather enigmatic N northeast- trending strike-slip zones is that they are pre-Quaternary and apparently offset the Cap au Gres structure; thus they are post-Middle Pennsylvanian. Their kinematics indicate a northeast­ southwest-directed, horizontal, maximum-principal stress. If the St. I Louis fault zone is also a strike-slip fault, then these structures occur across an interval in excess of 50 mi width.

0 500 FEET

REFERENCES CITED

Figure 2. Geologic sketch map of strike-slip faults found in the Amsden, T.W., 1974, Late Ordovician and Early Silurian articulate Alton Bluffs area, Ill. Road shown is State Route 3. brachiopods from Oklahoma, southwestern Illinois, and east­ em Missouri: Oklahoma Geological Survey, Bulletin 119, 154 p. the map on sheet 2, there is a slight right-lateral offset of the --1983, Oolitic strata of the Keel Formation and Edgewood Waterloo-Dupo and Florissant dome structural trends by the St. Group (Late Ordovician to Early Silurian), Texas Panhandle Louis fault zone; unfortunately, critical intersections are beneath to the Mississippi Valley [abs.]: Geological Society of America, the Mississippi River. Elsewhere, however, right-lateral strike-slip Abstracts with Programs, v. 15, no. 4, p. 222-223. faults parallel to the St. Louis fault zone are well exposed in the St. ---1986, Paleoenvironment of the Keel-Edgewood oolitic Louis area and are described below. province and the Hirantian strata of Europe, USSR, and China; Part 1 of Amsden, T.W., and Barrick, J.E., Late Ordovician-Early Silurian strata in the central United States Strike-slip Faults in the St. Louis Area and the Hirantian Stage: Oklahoma Geological Survey, Bul­ letin 139, p. 1-55. Along the Mississippi River bluffs from Alton, Ill., to Pere Anderson, K.H., 1979, Geologic map of Missouri: Missouri Geo­ Marquette State Park, Ill., several strike-slip faults that have logical Survey and Water Resources, scale 1:500,000. north-northeast and northeast strikes occur. Two principal areas of Anderson, R.R., 1988, Phanerozoic structural features in the faulting are located immediately west of Alton along Illinois Route northern Midcontinent, U.S.A.: U.S. Geological Survey, Mis­ 3 (Alton Bluffs) and in Deer Lick Hollow. A subsidiary fault occurs cellaneous Field Studies Map MF-1835-E, scale a few hundred yards east of Grafton, Ill. 1:1,000,000. The existence of strike-slip faults in the Alton Bluffs has been Atherton, E., Collinson, C., .and Lineback, J.A., 1975, Mississip­ known for many years (Collinson and Swan, 1958; Treworgy, pian System, in Willman, H.B., and others, Handbook of 1979); however, their orientation and sense of motion have never Illinois Stratigraphy: Illinois State Geological Survey, Bulletin been evaluated. These faults cut the Mississippian St. Louis 95, p. 123-193. Limestone across a zone in excess of 1,000 ft wide (fig. 2). Baxter, J.W., 1965, Limestone resources of Madison County, Quaternary loess appears unaffected by the faults. Fault sets strike Illinois: Illinois State Geological Survey, Circular 390, 39 p., 1 N. 45°-70° E. and N-5°-10° E. The more northeasterly set is on plate. strike with and parallel to the previously discussed St. Charles Branson, E.B., 1918, Geology of Missouri: Missouri University geophysical anomaly (see map on sheet 2); the other set is parallel Bulletin, v. 19, no. 15, p. 64, 66. to the St. Louis fault. Brill, K.G., Jr., Wallace, G.E., and Frank, A.J., 1960, Middle Both fault sets are vertical and consist of numerous, braided Mississippian and Pennsylvanian stratigraphy of St. Louis and strands. Horizontal slickenside striations are well developed on St. Louis County, Missouri, in Guidebook, Association of both sets, as is horizonally elongated, fibrous calcite mineralization. Missouri Geologists 7th Annual Meeting, October 7--8, 1960, Fiber ends are attached to irregularities (steps) on the fault surfaces. 13 p.

4 Brown, W.G., 1988, Basement involved tectonics foreland areas: Howe, W.B. (coordinator), and Koenig, J.W., ed., 1961, The American Association of Petroleum Geologists, Continuing stratigraphic succession in Missouri: Missouri Geological Sur­ Education Course Note Series No. 26, 92 p. vey and Water Resources, 2d series, v. 40, 18,5 p. Buschbach, T.C., 1964, and Ordovician strata of north­ Howe, W.B., Kurtz, V.E., and Anderson, K.H., 1972, Correlation eastern Illinois: Illinois State Geological Survey, Report of of Cambrian strata of the Ozark and Upper Mississippi Valley Investigations 218, 90 p. regions: Missouri Geological Survey and Water Resources, Clendenin, C.W., Middendorf, M.A., Thompson, T.L., and Whit­ Report of Investigations 52, 60 p. field, J.W., 1993, Structural style of the Eureka fault system, Kelley, V.C. 1955, Monoclines of the Colorado Plateau: Geolog­ eastern Missouri [abs.]: Geological Society of America, ical Society of America Bulletin, v. 66, p. 789-804. Abstracts with Programs, v. 25, no. 3, p. 13. Keyes, C.R, 1898, Some geological formations of the Cap-au­ Cole, V.B., 1961, The Cap au Gres fault: Missouri Geological Gres uplift: Iowa Academy of Sciences Proceedings, v. 5, p. Survey and Water Resources, Report of Investigations 27, 58-63. p. 86-88. Kissling, D.L., 1961, Lower Osagean stratigraphy of east-central Collinson, Charles, and Swann, D.H., 1958, Mississippian rocks of Missouri, in Guidebook, 26th Regional Field Conference, western Illinois: Geological Society of America Guidebook Kansas Geological Society, northeastern Missouri and west­ Series, Field Trip Guidebook St. Louis Meeting, 1958, Field central Illinois: Missouri Geological Survey and Water Trip No. 3, p. 21-32. Resources, Report of Investigations 27, p. 75-80. Collinson, Charles, Norby, RD., Thompson, T.L., and Baxter, Kisvarsanyi, E.B., 1974, Operation Basement: buried Precambrian J. W., 1979, Stratigraphy of the Mississippian stratotype-upper rocks of Missouri-their petrography and structure: American Mississippi Valley, U.S.A: Field Trip No.8 of the 9th Interna­ Association of Petroleum Geologists Bulletin, v. 58, p. tional ~ongress of Carboniferous Stratigraphy and Geology: 674-684. Illinois State Geological Survey, 108 p. --1975, Data on Precambrian in drillholes of Missouri includ­ Cote, W.E., Reinertsen, D.L., Wilson, G.M., and Killey, M.M., ing rock type and surface configuration (Contribution to 1970, Millstadt-Dupo area: Illinois State Geological Survey, Precambrian geology No.5): Missouri Geological Survey and Guide leaflet to Geological Science Field Trip, 33 p. Water Resources, Report of Investigations 56, 24 p. 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Howe, W.B., coordinator, and Koenig, J.M., ed., The strati­ Martin, J.A., and Wells, J.S., 1966, Guidebook to Middle Ordovi­ graphic succession in· Missouri: Missouri Geological Survey cian and Mississippian strata, St. Louis and St. Charles and Water Resources, 2d series, v. 40, p. 14-20. Counties, Missouri, 1966 Annual Meeting, American Associ­ Heigold, P.C., 1976, An aeromagnetic survey of southwestern ation of Petroleum Geologists: Missouri Geological Survey Illinois: Illinois State Geological Survey, Circular 495, 28 p. and Water Resources, Report of Investigations 34, 48 p. Hinchey, N.S., Fisher, RB., and Calhoun, W.A., 1947, Lime­ Mateker, E.J., Phelan, M.J., and Scharon, L., 1966, Geophysical stones and dolomites in the St. Louis area: Missouri Geolog­ evidence for a northeast crustal lineament near St. Louis ical Survey and Water Resources, Reports of Investigations 5, [abs.]: American Geophysical Union, Transactions, v. 47, p. 80p. 192.

5 McCracken, M.H., 1966, The structural features of St. Louis --1991, Paleozoic succession in Missouri; Part 2, Ordovician County and vicinity, in Martin, J.A., and Wells, J.S., eds., System: Missouri Department of Natural Resources, Division Guidebook to Middle Ordovician and Mississippian strata, ~t. of Geology and Land Survey, Report of Investigations No. 70, Louis and St. Charles Counties, Missouri: Missouri Geological 282 p. Survey and Water Resources, Report of Investigations 34, p. Thompson, T.L., and Satterfield, I.R., 1971, Ordovician-Silurian 38-41. boundary in eastern Missouri [abs.]: Geological Society of --1971, Structural features of Missouri: Missouri Geological America, Abstracts with Programs, v. 3, no. 4, p. 283. Survey and Water Resources, Report of Investigations 49, 99 --1975, Stratigraphy and conodont biostratigraphy of strata p. contiguous to the Ordovician-Silurian boundary in eastern Missouri Geological Survey, 1975, The resources of St. Charles Missouri: Missouri Geological Survey and Water Resources, County, Missouri-Land, water, and minerals: Missouri Report of Investigations 57, pt. 2, p. 61-108. Department of Natural Resources, Miscellaneous Publication Tikrity, S.S., 1968, Tectonic genesis of the Ozark uplift: St. Louis, MP-29, 237 p. Washington University, unpublished Ph.D. dissertation, 196 Muehlberger, W.R., Hedge, C.E., Denison, R.E., and Marvin, R.F., 1966, Geochronology of the Midcontinent region, United p. States; Part III, Southern area: Journal of Geophysical Treworgy, J.D., 1979, Structure and Paleozoic stratigraphy of the Research, v. 71, p. 5409-5426. Cap au Gres faulted flexure in western Illinois: Illinois State Nelson, W.J., and Lumm, O.K., 1985, Ste. Genevieve fault zone, Geological Survey, Guidebook 14, Trip 1, p. 1-35. Missouri and Illinois: U.S. Nuclear Regulatory Commission, Tucker, R.D., Krough, T.E., Ross, R.J., Jr., and Williams, S.H., ISGS Contract/Grant Report 1985-3, 94 p. 1990, Time-scale calibration by high-precision U-Pb zircon Odom, I.E., Wilson, G.M., and Dow, G., 1961, Valmeyer area: dating of interstratified volcanic ashes in the Ordovician and Illinois State Geological Survey, Guide leaflet to Geological Lower Silurian stratotypes of Britain: Earth and Planetary Science Field Trip, 18 p. Science Letters, v. 100, p. 51-58. Phelan, M.J., 1969, Crustal structure in the central Mississippi Weller, J.M., 1939, Generalized stratigraphic and structure section Valley earthquake zone: St. Louis, Washington University, of Illinois Bluffs of Mississippi River from East St. Louis to unpublished Ph.D. dissertation, 166 p. Thebes: Kansas Geological Society, 13th Annual Field Con­ Reches, Z., and- Johnson, A.M., 1978, Development of mono­ ference Guidebook, p. 14-15. clines: Part II. Theoretical analysis of monoclines, in Matthews, Weller, Stuart, 1906, Kinderhook faunal studies. N. The fauna of V., III, ed., Laramide folding associated with basement block the Glen Park limestone: St. Louis Academy of Sciences faulting in the western United States: Geological Society of Transactions, v. 16, no. 7, p. 435-471. America, Memoir 151, p. 273-311. --1907, Notes on the geology of southern Calhoun County: Rubey, W.W., 1952, Geology and mineral resources of the Hardin Illinois State Geological Survey, Year-Book for 1906, Bulletin and Brussels quadrangles: U.S. Geological Survey, Profes­ No.4, p. 219-233. sional Paper 218, 179 p. Weller, Stuart, and St. Clair, Stuart, 1928, Geology of Ste. Schultz, A.P. (compiler), 1993, Map showing surficial geology of Genevieve County: Missouri Bureau of Geology and Mines, v. the St. Louis 30 x 60 minute quadrangle: U.S. Geological 22,352 p. Survey, Open-File Report 93-288. Sims, P.K., Kisvarsanyi, E.B., and Morey, G.B., 1987, Geology Whitfield, J. W., 1989, Bedrock geologic map of the Defiance 71/z' and metallogeny of Archean and Proterozoic basement ter­ quadrangle, St. Charles County, Missouri: Missouri Geological ranes in the Northern Midcontinent, U.S.A-An overview: Survey and Water Resources, Department of Natural U.S. Geological Survey, Bulletin 1815, 51 p. Resources, Open-File Map OFM-89-255-GI, scale 1:24,000. Spreng, A.C., 1961, Mississippian System, in The stratigraphic Willman, H.B., Atherton, E., Buschbach, T.C., Collinson, C., Frye, succession in Missouri: Missouri Geological Survey and Water J.C., Hopkins, M.E., Lineback, J.A., and Simon, J.A., 1975, Resources, 2d series, v. 40, p. 49-78. Handbook of Illinois Stratigraphy: Illinois State Geological Templeton, J.L., and Willman, H.B., 1963, Champlainian Series Survey, Bulletin 95, 261 p. (Middle Ordovician) in Illinois: Illir10is State Geological Sur­ Willman, H.B., and Frye, J.C., 1958, Problems of vey, Bulletin 898, 260 p. geology in the greater St. Louis area: Geological Society of Thompson, T.L., 1975, Redescription and correlation of the Fern America, Guidebook for St. Louis Annual Meeting, 2d Field Glen Formation of Missouri, in Studies in Stratigraphy: Mis­ Trip, p. 9-19. souri Department of Natural Resources, Division of Research Willman, H.B., and Kolata, D.R., 1978, The Platteville and Galena and Technical Information, Geological Survey, Report of Groups in northern Illinois: Illinois State Geological Survey, Investigations 57, pt. 5, p. 141-172. Circular 502, 75 p. --1986, Paleozoic succession in Missouri; Part 4, Mississippi Zietz, Isidore, Bond, K.R., and Riggle, F.E., 1984, The magnetic System: Missouri Department of Natural Resources, Division anomaly map of Missouri with an interpretation of Precam­ of Geology and Land Survey, Report of Investigations No. 70, brian structure; Part A: Missouri Department of Natural 182 p. Resources, Contributions to Precambrian Geology No. 14.

6 APPENDIX A. Source material used to compile the geologic map of the St. Louis 30' x 60' quadrangle. Numbers correspond to those on the index map on sheet 1.

1. Martin, J.A., 1960, Reconnaissance geologic map of the Troy 15' logical Survey and Water Resources, Department of Natural quadrangle: Missouri Geological Survey and Water Resources, Open-File Map SL-5116, scale 1:31,250. Resources, Department of Natural Resources, Open-File Map 8. SL-6008, scale 1:62,000. Danielson, R.E., 1956, Geology of a portion of the Augusta Unpublished data from water-well logs on file at the Missouri quadrangle, Franklin and St. Charles Counties, Missouri: Geological Survey and Water Resources, Department of Missouri Geological Survey and Water Resources, Depart­ Natural Resources, Rolla. ment of Natural Resources, Open-File Map SL-5603, scale 2. 1:24,000 [also as unpublished M.S. thesis, Washington Uni­ Missouri Geological Survey, 1975, The resources of St. Charles versity, St. Louis]. County, Missouri-Land, water, and minerals: Missouri 9. Department of Natural Resources, Miscellaneous Publication Unpublished data from water-well logs on file at the Missouri MP-29, 237 p. Geological Survey and Water Resources, Department of Satterfield, I.R., 1973, Reconnaissance map of St. Charles County: Natural Resources, Rolla. Missouri Geological Survey and Water Resources, Depart­ 10. ment of Natural Resources, Open-File Map SL-7301, scale Rubey, W.W., 1952, Geology and mineral resources of the Hardin 1:24,000. and Brussels quadrangles: U.S. Geological Survey, Profes­ Satterfield, I.R., 1973, Reconnaissance map of western St. Charles sional Paper 218, 179 p. County:· Missouri Geological Survey and Water Resources, 11. Department of Natural Resources, Open-File Map SL-7302, Missouri Geological Survey, 1975, The resources of St. Charles scale 1:48,000. County, Missouri-Land, water, and minerals: Missouri 3. Department of Natural Resources, Miscellaneous Publication Martin, J.A., 1960, Reconnaissance map of the Augusta 15' MP-29, 237 p. quadrangle: Missouri Geological Survey and Water Satterfield, I.R., 1973, Reconnaissance map of St. Charles County: Resources, Department of Natural Resources, Open-File Map Missouri Geological Survey ·and Water Resources, Depart­ SL-6007, scale 1:62,500, 2 sheets. ment of Natural Resources, Open-File Map SL-7301, scale 4. 1:24,000. Martin, J.A., 1960, Reconnaissance map of the Augusta 15' 12. quadrangle: Missouri Geological Survey and Water Brill, K.G., Jr., 1991, Geologic map of St. Louis City and County, Resources, Department of Natural Resources, Open-File Map Missouri: Missouri Geological Survey and Water Resources, SL-6007, scale 1:62,500, 2 sheets. Open-File Map OFM-91-259-GI, scale 1:63,360. Satterfield, I.R., 1973, Reconnaissance map of western St. Charles Fenneman, N.M., 1911, Geology and mineral resources of the St. County: Missouri Geological Survey and Water Resources, Louis quadrangle, Missouri-Illinois: U.S. Geological Survey, Department of Natural Resources, Open-File Map SL-7302, Bulletin 438, 73 p. scale 1:48,000. 13. 5. Baxter, J.W., 1970, Limestone and dolomite resources of Jersey Whitfield, J.W., 1989, Bedrock geologic map of the Defiance County, Illinois: Illinois State Geological Survey, Circular 448, 71/2' quadrangle, St. Charles County, Missouri: Missouri Geo­ 26 p., 1 plate. logical Survey and Water Resources, Department of Natural 14. Resources, Open-File Map OFM-89-255-GI, scale 1:24,000. Baxter, J.W., 1965, Limestone resources of Madison County, 6. Illinois: Illinois State Geological Survey, Circular 390, 39 p., 1 Martin, J.A., 1959, Reconnaissance map of E 112 of Washington plate. 15' quadrangle: Missouri Geological Survey and Water Odom, I.E., 1971, Clay and shale resources of Madison, Monroe, Resources, Department of Natural Resources, Open-File Map and St. Clair Counties, Illinois: Illinois State Geological Sur­ SL-5907, scale 1;31,700. vey, Industrial Minerals Notes 45, 18 p. 7. 15. Satterfield, I.R., 1973, Reconnaissance map of western St. Charles Jacobs, A.M., compiler, 1971, Geology for planning in St. Clair County: Missouri Geological Survey and Water Resources, County, Illinois: Illinois State Geological Survey, Circular 465, Department of Natural Resources, Open-File Map SL-7302, 35 p., 8 plates. scale 1:48,000. Odom, I.E., 1971, Clay and shale resources of Madison, Monroe, Schindler, J.F., 1951, Geologic map of a portion of the Augusta and St. Clair Counties, Illinois: Illinois State Geological Sur­ 15' quadrangle, St. Charles County, Missouri: Missouri Geo- vey, Industrial Minerals Notes 45, 18 p.

7