Geology of the Peebles Quadrangle, Adams County, Ohio1
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Copyright © 1985 Ohio Acad. Sci. 0030-0950/85/0005-0218 $2.00/0 GEOLOGY OF THE PEEBLES QUADRANGLE, ADAMS COUNTY, OHIO1 E. MAC SWINFORD2, Department of Geology, Eastern Kentucky University, Richmond, KY 40475 ABSTRACT. The rock sequence exposed in the Peebles quadrangle, Adams Co., Ohio, consists of over 240 m of Ordovician through Mississippian age rocks. These carbonate rocks, shales, and sandstones have been subdivided into 13 formations. Units which have been recently recognized in this area include the Bull Fork Formation (Upper Or- dovician), the Preachersville Member of the Drakes Formation (Upper Ordovician), the Drowning Creek Formation (Silurian), and the Three Lick Tongue of the Chagrin Member of the Ohio Shale (Upper Devonian). These strata generally dip 6—8 m per km to the east, but the dip increases to 10—11 m per km in the southeast portion of the quadrangle. The increase in dip is due to the Adams Co. monocline. The monocline is thought to be the result of draping of Paleozoic rocks over a possible basement fault. OHIOJ. SCI. 85 (5): 218-230, 1985 INTRODUCTION Peebles quadrangle will contribute to a A thorough understanding and docu- better understanding of Adams Co. geology. mentation of an area's geology is of prime Existing published bedrock investi- importance to the explorationist and ge- gations on Adams Co. are limited to por- ologist. The data can be effectively used in tions of the stratigraphic section, with only planning for recreational facilities, waste a few exceptions. John Locke studied disposal dumps, and industrial complexes. Adams Co. geology and produced the first Furthermore, these data are critical in de- county geologic map in the state of Ohio tecting water and mineral resources, as in 1838. More recent mapping projects well as engineering hazards. The combina- within Adams Co. include the geologic tion of a thorough literature search and a maps of the Maysville East quadrangle detailed field mapping program provides (Weiss et al. 1972) and the Serpent Mound this information most accurately. cryptoexplosion structure (Bucher 1936, Published information concerning the Reidel 1975). Unpublished geologic maps bedrock geology of Adams Co., Ohio, is include the Peebles quadrangle (Swinford surprisingly meager considering that the 1983) and the northwestern portion of county has abundant bedrock exposures Adams Co. (Kaufmann 1964). Other stud- and only minor glacial cover. Rocks within ies which address a substantial portion of this area are of diverse ages, lithologic the stratigraphic section of the area include types, and have significant regional and Bowman's (1956) study of the Niagaran local structural trends. The Peebles quad- rocks of Highland County, Rexroad et al. rangle located in northeast Adams Co. (1965) study of the Silurian of southern (fig. 1) has all of these characteristics Ohio and northern Kentucky, and Kallio's which allow for an exceptionally pro- (1976) study of the Silurian along Ohio ductive study of the area's geology. Docu- Brush Creek in Adams Co. The soil survey menting the geologic setting within the of Adams Co. (Taylor 1938) provides addi- tional information on the presence of bed- xManuscript received 3 July 1985 and in revised rock and its effect on soil and topography. form 30 September 1985 (#85-26). 2Present Address: Ohio Department of Natural METHODS AND MATERIALS Resources, Division of Geological Survey, Fountain Traditional techniques and instruments were uti- Square, Bldg. B, Columbus, OH 43224 lized in gathering data on the rocks of the Peebles 218 OhioJ. Sci. GEOLOGY OF THE PEEBLES QUADRANGLE 219 and majority of the Peebles quadrangle consists of the Interior Low Plateau region. This topography contains low rolling hills with some moderately steep-walled valleys which have 30—61 m of relief. The abrupt change of the rugged topography of the Appalachian Plateau to the landforms of the Interior Low Plateau creates a boundary called the Appalachian Escarpment. The escarpment is present in the southeast por- tion of the Peebles quadrangle as a north- east-trending lineament. Ohio Brush Creek and Scioto Brush Creek are the main drainage basins within the Peebles quadrangle. Ohio Brush Creek, centrally located within the quad- rangle, flows southward toward the Ohio PEEBLES River. Ohio Brush Creek and tributaries of QUADRANGLE this stream are responsible for a majority of ADAMS the topographic dissection of the study COUNTY area. Creeks flowing eastward in the south- eastern portion of the quadrangle drain into Scioto Brush Creek which lies 10 km east of the study area. FIGURE 1. Location of the Peebles quadrangle, STRATIGRAPHY. The entire rock strati- Adams Co., Ohio. graphic section within the Peebles quad- quadrangle. Instruments used in the field were a rangle consists of more than 244 m of Paulin Terra altimeter, hand level, Brunton com- Ordovician, Silurian, Devonian and pass, and base maps of the Peebles and surrounding Mississippian age rocks. Thirteen separate quadrangles. The elevation of 714 data points was formations and four unconformities were documented with an altimeter. Numerous strati- identified within the stratigraphic section graphic sections within the Peebles quadrangle were measured with a hand level or rule. Unusually thick (fig. 2). Rocks within the study area can sections (particularly in homogenous shales) were be separated into general lithologic groups also measured with an altimeter to confirm hand according to their age. Upper Ordovician level estimations. Elevation of data points and for- and Lower Silurian rocks are dominantly mation thicknesses of measured sections were used thin-bedded limestones and shales. Middle to produce structure contour and isopach maps at a 1:24,000 scale. Aerial photographs were also used and Upper Silurian rocks are thick, unin- to delineate terrace and alluvial deposits along terrupted sequences of carbonates or clay streams. A geologic map was constructed from this shales. Devonian rocks are mainly dark, data and is on file at the Ohio Department of Natu- petroliferous shales with some greenish- ral Resources, Division of Geological Survey. gray shales. Lower Mississippian rocks are DISCUSSION silty shales and sandstones. Each of the Two physiographic regions occur within units will be described with other rock the Peebles quadrangle, the Appalachian units of similar geologic age. Plateau and the Interior Low Plateau. The ORDOVICIAN. The oldest rocks ex- Appalachian Plateau region occurs in the posed in the Peebles quadrangle are Upper southeast edge of the quadrangle. This to- Ordovician age carbonates and shales. Peck pography consists of high narrow ridges (1966), in conjunction with the Kentucky with steep-walled valleys having an aver- geologic mapping program, described and age relief of 61—122 m. The remainder defined rocks of Richmondian age in the 220 E. M. SWINFORD Vol. 85 FORMATION S MEMBER LITHOLOGY ALLUVIUM BEREA SANDSTONE BEDFORD SHALE N DEVONIA OLENTANGY SHALE TYMOCHTEE DOLOMITE GREENFIELD DOLOMITE PEEBLES DOLOMITE N LILLEY Fm. BISHER Fm. SILURIA ESTILL SHALE DRAKES BULL FORK Fm. FIGURE 2. Generalized stratigraphic column of the rocks found within the Peebles quadrangle. OhioJ. Sci. GEOLOGY OF THE PEEBLES QUADRANGLE 221 vicinity of Maysville, Kentucky. These units were mapped in the Ohio portion of the Maysville East quadrangle (Weiss et al. 1972) in Adams and Brown counties. The use of Peck's nomenclature is accepted within the Peebles quadrangle and in- cludes the Bull Fork Formation and the overlying Preachersville Member of the Drakes Formation. The Bull Fork Formation consists of very fossiliferous interbedded limestones and shales. The limestones are light to blu- ish gray, medium to coarse grained, in beds 9—30 cm thick and are dolomitic. A particularly good exposure reveals thin limestones grouped into continuous bands 30—39 cm thick separated by shale beds approximately 9 cm thick. The Bull Fork is discontinuously ex- posed along Ohio Brush Creek and western 1km tributaries of this stream. The best expo- FIGURE 3. Location of best exposures for rocks sures of these rocks occur in the Little East found in the study area. Locality 1: Bull Fork Fm. Fork 0.4 km south of the intersection with (upper portion), Drakes Fm., and Drowning Creek State Route 32 where the uppermost Fm. (lower portion). Locality 2: Drakes Fm. 3.1 m are exposed (fig. 3, locality 1). (upper portion), and Drowning Creek Fm. Locality 3: Drowning Creek Fm. (Dayton The lack of exposure of the lower contact Mmbr.), Estill Shale, Bisher Fm., and Lilley Fm. of the Bull Fork Formation prohibits deter- Locality 4: Estill Shale (upper portion), Bisher mination of its thickness within the study Fm., Lilley Fm., and Peebles Dolomite (transitional area. The upper contact of the Bull Fork zone). Locality 5: Bisher Fm., Lilley Fm., Peebles Dolomite, Greenfield Dolomite, and Tymochtee with the overlying Preachersville Member Dolomite within Plum Run Quarry. Local- of the Drakes Formation is conformable ity 6: Greenfield-Tymochtee Dolomites, Olen- and gradational over a 0.3-m interval. The tangy Shale, Ohio Shale, Bedford Shale, and Berea contact is placed at the top of the highest Sandstone. continuous fossiliferous limestone layer of the Bull Fork Formation (Peck 1966). The Drakes Formation appears as dis- The Preachersville Member of the continuous exposures along Ohio Brush Drakes Formation, hereafter referred to as Creek and tributaries of the stream much the Drakes Formation, consists chiefly of the same as the Bull Fork Formation. It mudstone with thin discontinuous dolo- can easily be recognized by the distinctive mite beds less than 6 cm thick. The mud- dusky-red color which appears in the over- stone is greenish gray to dusky red, lying soil. The best total section within the calcareous to dolomitic, locally silty and study area is located within the Little East fissile to platy. The dolomite beds are light Fork just south of the intersection with gray, calcareous in places, sparsely fossil- State Route 32 where an estimated 7.6 m iferous and argillaceous.