The Lafayette Bedrock Valley System is a complex of bedrock valleys that converge on and diverge from Lafayette, Indiana. The primary trunk valley of the system, composed of the narrow Marion Valley Section on the east and the broad Mahomet Valley Section on the west, is the classic “Teays Valley” of the Midwest. If such a continuous Teays drainage truly existed, it represents only the early part of the history of the Lafayette Bedrock Valley System in Indiana. Origins of the valley parts and their form remain enigmatic. Although the Marion crosses major rock structure, the course and the contrasting forms of the parts reflect structural and lithologic control. Contrasting valley forms, valley deeps, and possible inset benches may reflect one event or multiple events in a single valley, or disparate events in other valleys; or the features may reflect external events, such as incision through forebulge or erosion beneath bursting ice dams. Although the origins of the valley system are conjectural, the fill sequences within give evidence of the nature and timing of the demise of the system. The Marion valley is filled with a plug of old lacustrine and glaciolacustrine sediments included in the Blackford Member of the Banner and Jessup Formations. These sediments were deposited in a lake dammed between ice at the valley bends at Logansport, Indiana, and St. Marys, Ohio. Deposited at the dams were subaqueous fan deposits of coarse-grained outwash and tills of both basal-meltout and sediment gravity-flow origin. The tills include the red claystone-bearing West Lebanon Till Member on the west, and the Wilshire Till Member on the east. An uppermost tongue of the West Lebanon till caps the Blackford lacustrine sediments, indicating southeastward progression of the West Lebanon ice into the lake and ultimately over the entire fill sequence. The relative age of plugging of this valley section is suggested by the West Lebanon, which overlies magnetically reversed (>0.7-m.y.-old; marine isotopic stage 22?) sediments in western Indiana. The plugging of the Marion valley by West Lebanon ice corresponds in time with the plugging of the valley in Ohio by Wilshire ice (and the deposition of the Minford Silts) and marks the end of classic Teays-stage regional drainage. The Mahomet valley subsequently was reexcavated as part of a Metea-Mahomet drainage system, heading in northeastern Indiana. This valley is filled with younger, interfingered outwash and till, which are included in the Mahomet Member and the Brookston Till Member of the Banner and Jessup Formations. These deposits represent aggrading braided stream and fan environments in front of southwestward-advancing Brookston ice. The relative age of plugging of this valley section is given by the Vandalia Till Member of the Glasford Formation, an Illinoian till that caps the valley fill, and by the West Lebanon till, which was apparently cut out prior to valley filling. The final plugging of the Mahomet marks the end of any deeply incised drainage in north-central Indiana. With the demise of the Mahomet drainage outlet, development of an upper Wabash drainage system began. The fill of bedrock valleys south of the Marion-Mahomet trunk valley contains evidence of multiple erosional surfaces. The gradients of these surfaces suggest a merging at Lafayette into early equivalents of the modern Wabash drainage, exiting into the Wabash bedrock valley via the Attica cutoff or across the rock sill above Independence.

Groundwater resources associated with sediments filling the Marion and Mahomet Valley Sections of the Lafayette Bedrock Valley System vary from miniscule to substantial, reflecting the wide range of glacigenic aquifer facies contained in the fill. These aquifer facies include braid-stream deposits that range from thin units within till sequences to immense, valley-filling masses. Also included is a variety of proximal to distal, subaerial to subaqueous, fan and fan-delta deposits; these range from thick masses of ice-proximal, cobbly rubble interspersed with thin diamicts and clays, to thin, discontinuous lentils of sand confined within lacustrine clays. Valley-fill aquifers are confined by capping till units, except where exhumed at the crossings of the Maumee-Wabash Trough (modern Wabash River Valley). A variety of aquifers typically are available within the valley-capping sediments; for this reason, much of the deep valley-fill has not been extensively explored or developed. Some valley-fill aquifers are so thin and/or deeply buried that their exploitation is unlikely, but others are so thick and areally extensive that exploitation easily can support sustainable yields of tens of millions of gallons per day.

Abstarct The glacial geology of the area north of the Great Bend of the Wabash River in west-central Indiana (Fig.1), 1) illustrates important early developed principles regarding multiple continentalglaciation, the movements of adjoining ice lobes, and the interrelated deposits. Perhaps the first documentation of a lithologically definable till stratigraphy that is basic to interpretation of glacial movement and sedimentation throughout much of the Midwest was made in the Great Bend area. A half century after the first documentation was made, the till stratigraphy here would emerge as the regionally mappable sequence. Further, it would illustrate cross-cutting relationships of morainal ridges andthe interbedding of multiple-source deposits. Here, therefore, is a clear demonstration of how deposits first classified on the basis of surface morphology relate to those that are classifiable on a mappable, till-stratigraphy basis. Four vantage points in the Great Bend area are particularly focal for illustration ofthe basic concepts that are addressed here.Foremost is the Lovers Leap section (also known historically as the Stone Creek section), which is exposed on the northwest side of Big Pine Creek, a Wabash River tributary, 4 mi (6.4 km) north of Williamsport, Warren County, Indiana, NW¼NW¼ NW¼Sec.23, T.22N., R.8W., Williamsport 7½-minute Quadrangle (Fig. 2d), 2D). Here well exposed are three superimposed tills and other drift materials that a pioneer of continental-glaciation theories, Thomas Chrowder Chamberlain, used to demonstrate his beliefs. In fact, our Figure 3 is taken from Chamberlin’s contribution to James Geike’s ( 1894) The Great Ice Age and was

Abstract The Cataract Lake emergency spillway in Putnam County, Indiana, is in the SW¼NW¼ Sec.13, T.12N., R.5W. (Poland Quadrangle). The spillway cut is most easily reached by following the secondary road indicated in Figure 1 north from Indiana 42, a distance of about 2 mi (3.2 km). The secondary road thatleads to the spillway cut is identified by a Corps of Engineers sign that points the way to the reservoir dam. The intersection of Indiana 42 with the road to the spillway is about 5 mi (8 km) south of 1-70 and is 1.8 mi (3 km) east of Poland, Indiana, and 4.6 mi (7.4 km) west of the intersection of Indiana 243 and Indiana 42 (Fig. 1). The spillway cut is immediately adjacent to the secondary road that runs north from Indiana 42. Because the spillway cut is a restricted area, permission to enter should be obtained at the Corps of Engineers office just north of the dam.