The exposed and abandoned Teays Valley has been recognized and studied in south-central Ohio for a century and a half. By 1900, the upper reaches had been traced by bedrock strath up present deeper drainages through West Virginia into Virginia. By 1945, the 1.5-mi-wide main valley had been traced downstream by water/oil wells, under several glacial drifts, northward and westward from Chillicothe, Ohio, to Indiana. The average gradient in this reach is northwest 0.9 ft/mi. Horberg and others carried this valley westward to the Mahomet buried drainage of Illinois. Discontinuities such as in Madison County, Ohio, have been explored by geophysical profiles and test wells and show a marked narrowing into a canyon cut through resistant dolomites. As late as the 1970s, the largest tributary, which drains most of eastern Kentucky northward and on either side of Cincinnati, has been added. More and more basal floodplain sands/gravels and northward-inclined crossbeds are found in all these meandering valleys beyond the glacial limit. Near the limit these deposits are covered with lacustrine clay rhythmites, which grade to silty and then into sandy outwash containing glacially derived northern clasts. Clearly, glaciation dammed the valley system westward out of Ohio. This blockage was early Pleistocene, certainly pre-Illinoian, because clays are magnetically reversed. Other blockages took place southwestward from Cincinnati at a later date. The exposed Minford Clays in southcentral Ohio and western West Virginia must have filled to near the present 900-ft contour, because the former, dendritic Teays drainage is criss-crossed by an aimless, superimposed drainage that postdates the Deep Stage.

Three transects were conducted across the main channel of the abandoned Teays River valley in Pike, Jackson, and Scioto Counties, Ohio, to evaluate the lithology and general stratigraphy of valley-fill deposits. Field observations obtained from both deep borings and surface excavations indicate that much of the Pleistocene lacustrine fill has been removed and that the modern landscape reflects primarily a sequence of erosional and secondary fill surfaces. Thus, the current valley fill includes lacustrine clays and channel sands, as well as younger sediments of varied origin. A general sequence of three sedimentary stratigraphic units was commonly encountered in the transects. A silty surface unit overlay an intermediate deposit, which in turn, rested on channel sands or on highly laminated lacustrine materials that were equated with the Minford Clay Member of the Teays Formation. The silty surface unit occurred at almost all sites to a depth of 50 to 60 cm. The mineralogy was mixed, and clay-free particle-size profiles indicated the material was loessial in origin. The intermediate deposit was also encountered in most borings and could be classified as colluvial, alluvial or lacustrine depending on the location. The lithology of this deposit was highly variable and frequently reflected the properties of local bedrock units. Minford Clay was distinguished from younger lacustrine sediments of the intermediate unit on the basis of higher clay content, more micaceous mineralogy, and an elemental Zr content that was two to four times less. Discriminant statistical analyses of data from a total of 180 samples indicated that the Minford Clay could also be easily distinguished from all other Quaternary sediments in the Teays Valley on the basis of selected chemical attributes. By using the same parameters, however, lacustrine deposits in overlying stratigraphic units could not be clearly separated from associated colluvium, alluvium, and loess.

Configuration of the buried part of the Teays Valley system across western Ohio, Indiana, and eastern Illinois suggests that the Teays is not a preglacial system, but rather, that it was formed marginal to a major glacier earlier than that which created the Ohio River, probably in similar fashion by consolidating and diverting fragments of older drainages. Pertinent criteria include (1) the relatively straight gorge that (2) crosses at least three regionally high areas with (3) few tributaries that join at grade. Also significant are (4) the depth of the gorge across a broad limestone plateau that has (5) relatively shallow karst development. These features imply a youthful valley system that was destroyed by burial before reaching a mature stage. Although thousands of drillholes and seismic datum points in Indiana alone detail the bedrock surface and the nature of the unconsolidated deposits that overlie it, many questions remain regarding the evolution of that surface. Fluvial and lacustrine deposits associated with the earliest presently known till in Indiana (>0.8 Ma) fill eastern parts of the Teays gorge. Are there tills of pre-Teays age, and is any part of a pre-Teays valley system identifiable? What stratigraphic criteria distinguish those parts of the Teays that have been reoccupied and incorporated into younger, but now also buried, valley systems? The Blue River Strath of southern Indiana shares many characteristics with the type Teays and the ancestral Kentucky River valley and may be coeval with them; are there other such features? A regional approach to these and related questions should yield results.

At some time during the Pleistocene Epoch, a part of the modern Ohio River drainage system in Ohio and West Virginia developed in response to impoundment of the ancestral Teays River drainage system. Rhythmites formed in the lacustrine slackwaters and remain today, extending as much as 150 to 200 km upstream from the Pleistocene ice front, in Teays Valley, West Virginia. A total of 303 oriented paleomagnetic specimens represent a composite stratigraphic section from the Minford Silt Member of the Teays Formation in Teays Valley. Of these, 224 specimens carry a stable reversed magnetization due to detrital magnetite and hematite. Two distinctive lithologic intervals with definitive magnetic intensities were found in the stratigraphic section; thick, light-colored rhythmites carry six times more remanent magnetization intensity than thin, dark-colored rhythmites, reflecting variations in the ratio of magnetite to hematite. From the Pleistocene paleomagnetic chronology, the glacial diversion of the Teays River in Ohio and West Virginia took place during the Matuyama reversed polarity chron, in the time interval between 0.79 and 1.60 Ma, the change attributed to an Early Pleistocene age, most probably the F or G glaciation. We propose that the Minford Silt was deposited between 0.79 and 0.88 Ma.

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.

ABSTRACT About 17,000 yr ago, Glacial Lake Maumee breached the Fort Wayne Moraine, sending an unimaginably large torrent of meltwater down the upper Wabash River Valley (UWRV). The Maumee Megaflood (MM) may have lasted only a few weeks, but it scoured out a deep trough along the main stem of the river, radically lowering regional base level in what amounts to a geological instant and imposing a strong disequilibrium on a landscape that continues to experience major geomorphic, environmental, and ecological adjustments. In Huntington and Wabash Counties, the central part of the trough is engorged in resistant, Late Silurian reef-associated and inter-reef rocks, producing the largest natural bedrock exposure in heavily glaciated northern Indiana. Unlike the immature, deranged drainage pattern that characterizes most of the glaciated region, streams adjacent to the UWRV form well-integrated drainage networks that exhibit features and processes more typical of high-relief bedrock areas, such as steep fall zones with prominent, lithologically controlled knickpoints, canyons, large terraces, falls and cascades, and a variety of bluff and hillside morphologies and associated groundwater phenomena. The exceptional exposures and diverse landscape of this region have attracted well over a century of interest from geomorphologists and glacial geologists, sedimentologists, stratigraphers, and paleontologists, as well as hydrogeologists, anthropologists, ecologists, and geoscience educators. Among other firsts, the organic origin of fossil reefs in the southern Great Lakes was definitively established in the UWRV, as was the occurrence of convulsive meltwater outbursts during deglaciation of the Laurentide Ice Sheet; likewise, the first direct Mississippi River–Great Lakes connection was also established here by early voyageurs. Today, the region is a popular destination for both nature tourism and history buffs, due in no small part to the burgeoning number of geologically inspired natural areas and historical sites. This field trip traces the MM from its outlet at Fort Wayne, through the bedrock gorge of the upper Wabash River, to the confluence with the late Tertiary Teays Bedrock Valley, with major emphasis on how the depositional framework and diagenetic history of the Late Silurian reef archipelago continue to reverberate in the modern geomorphic response of the valley to Pleistocene events. The first three stops focus on the Wabash-Erie Channel, which acted as the principal outlet of Glacial Lake Maumee and whose underlying geologic characteristics controlled the overall incision history of the MM. Several stops in the Wabash bedrock gorge and Salamonie Narrows will examine the handiwork of this flood, which created the spectacular klintar, or pinnacle-like reefs, of the UWRV, within a landscape that early geomorphologists likened to the scablands of eastern Washington. There, we will see world-class exposures of the fossilized Late Silurian reefs and how their organic framework and diagenesis are controlling the ongoing adjustment of the UWRV landscape and its streams to the convulsive changes imposed by the MM. Stop 9 will showcase the elusive Teays Bedrock Valley and its complex pre-Wisconsin fill, where it converges with the modern river and has been partially exhumed by a major tributary, and offers a study in contrasts between the bedrock-controlled landscapes of earlier stops and an equally steep one excavated entirely into unconsolidated deposits. After a brief stop at the iconic Seven Pillars landmark, the trip concludes at the spectacular Pipe Creek Jr. Quarry, which features several km of tall exposures through the Late Silurian carbonate complex, a late Neogene sinkhole deposit, and the overlying Pleistocene section.

The Old Kentucky River system was a major contributor to the Teays River, draining southwestern Ohio and much of eastern Kentucky. The trunk river flowed northward from southeastern Kentucky throughout Frankfort and Carrollton, and then past Cincinnati and Dayton, joining the Teays River near Springfield, Ohio. North of the glacial boundary, which lies along the modern Ohio River, the course of the Old Kentucky River has been modified, and is today largely buried by drift. Although dissection is extensive to the south, there are many remnants of this entrenched and broadly meandering Teays-age valley system and of its sub-upland predecessors. These valleys contain areas of upward-fining, deeply weathered gravel, composed mainly of rounded quartz, chert, and silicified limestone pebbles derived from the headwaters of the system. Modern rivers have been entrenched 30 to 100 m below the Old Kentucky River valley and its main tributaries, the Old Licking and South Fork. The Old Kentucky River system was severed from the Teays when glaciation dammed its downstream reaches, forcing a reversal in flow direction between its junction with the Teays in west-central Ohio and Carrollton, Kentucky, and causing westward overflow into the Old Ohio River system. Piracy by the Old Ohio may also have contributed to the integration of the Old Kentucky and Old Ohio River basins. Ponded sediment is present in some of the now-abandoned valley remnants east of Cincinnati. As a result of glacial damming, the headwaters of the Teays River in southeastern Ohio and West Virginia overflowed westward across the Manchester divide into the Old Kentucky River drainage basin. All of these events led to establishment of the modern Ohio River system.

ABSTRACT Pleistocene glacial and interglacial episodes had a profound influence on erosion, sediment transport, and topographic expression in the Midwestern United States. Northern Kentucky hosts a variety of fluvial and glacial features that record these Quaternary advances and retreats of the Laurentide ice sheet. This field trip highlights the major glacial and interglacial episodes of the Pleistocene, including the Pliocene–Early Pleistocene Teays drainage system, the Early–Middle Pleistocene pre–Illinois glacial Episode, the Middle Pleistocene Yarmouth interglacial, the Illinois glacial Episode in the Middle Pleistocene, the Sangamon interglacial, and the Late Pleistocene Wisconsin Episode. The Old Kentucky River was tributary to the Teays, depositing sands at ca. 1.5 Ma, confirmed by multiple 10 Be- 26 Al cosmogenic radionuclide burial ages. Glacial till uncoformably overlies Old Kentucky River sands and demonstrates that pre-Illinois ice extended into Kentucky. The modern-day course of the Ohio River was incised after the pre−Illinois Episode, and then aggraded with transportation of Illinois Episode glacial outwash. Deposition of outwash at the mouths of tributaries caused impoundment and slackwater deposition in tributary valleys; the Claryville Clay has long been assumed to represent a pre-Illinois lacustrine deposit, but new optically stimulated luminescence feldspar geochronology yields a Middle Pleistocene age of ca. 320 ka. We have not observed Illinoian till in Kentucky. The final advance of the Laurentide ice sheet did not reach Kentucky, however, high sediment volumes were transported along the Ohio River and impounded tributaries, similar to the Illinois Episode.