THE MICROSTRATIGRAPHY AND PALEONTOLOGY OF THE MEADVILLE SHALE MEMBER AT LODI, NORTHEASTERN OHIO: A PALEOENVIRONMENTAL ANALYSIS

The Meadville shale Member of northeastern Ohio and northwestern Pennsylvania is a series of alternating shales and interbedded siltstones. Historically speaking it has been divided into (in ascending order): (1) the Harvest Home Member, which is underlain by the Sharpsville sandstone and forms a gradational contact; (2) the French Creek limestone; and (3) the Custards shale Member, which is overlain by the Shenango sandstone, and forms a distinct unconformity. The Meadville shale Member has been interpreted by most workers to be of the Lower (Osagian) Mississippian period. This member, which is part of the larger Cuyahoga Formation, includes horizontal and low angle cross stratification, ripple and flow marks, and regional and local unconformities.

My research was conducted in southwestern Medina County, in northeastern Ohio. The specific sites were located in Lodi State Park, on the east bank of the East Branch of the Black River (on meridian 820 0' 47' Wand parallel 410 2' 24' N). At these sites, the Black River has exposed the Meadville shale Member.

The purpose of the study was: (1) to describe the microstratigraphy of the east bank of the East Branch of the Black River; (2) to describe the paleontology of the fossiliferous beds; (3) to identify the sedimentary structures; (4) to put the exposed beds of the Meadville shale Member at Lodi Park into a local stratigraphic context; (5) to interpret the field data in order to come to some conclusions about the overall environment and depositional sequence of the Lower (Osagian) Mississippian aged Meadville Shale Member.

I have identified the Meadville shale Member to be associated with a Mississippian (Osagian) marine regression of the Cuyahoga basin. The outcrops generally represent an upward coarsening lithologic sequence, with regressive mini-cycles. Fossiliferous beds (composed of bryozoans, brachiopods, and crinoid stems) found in shale and the underside of siltstone units, were most likely a result of a turbidite current or a storm related depositional event.