The surficial geology of Fulton county, Ohio: Insight into the late pleistocene-early holocene glaciated landscape of the Huron-Erie lake plain, Fulton county Ohio, USA.

摘要

The four-dimensional surficial geology of Fulton County, Ohio is presented to elucidate the Late Pleistocene-Early Holocene deglacial history of the Huron-Erie Lake Plain. Ice-walled lake plains and the previously mapped lower Maumee strandline were evaluated in detail to help resolve controversies regarding their origins. High resolution light detecting and ranging imagery, ground penetrating radar, and electrical resistivity imaging allow rapid and accurate surveying of subtle topographic features in the flat till plains of NW Ohio where natural exposures of the stratigraphy are scarce. Optically stimulated luminescence dating (OSL) provides ages of sandy surficial sediments which often lack datable organics. Five terrains were mapped based on depositional environments: alluvial, eolian, glacial, glacial fluvial, and glacial lacustrine, which are characterized of various packages of sand, sand and gravel, pebbly sand, clay silt, and clay silt diamict. Two texturally distinct tills were identified and correlate to the Early and Late Woodfordian tills documented in other areas of the Huron-Erie Lake Plain. Nine OSL ages collected from sandy surficial sediments range from 19.4 +/- 1.1 to 11.8 +/- 0.6 ka providing some absolute age control and giving insight into the deglacial history. The oldest age of 19.4 +/- 1.1 ka coincides with the Erie Interstadial and is older than the previously documented age of the Defiance Moraine. Auger borings of an ice-walled lake plain recovered interbedded sand and gravel underlain by clay diamict along its rim, while a resistivity survey imaged four inferred sediment types: lacustrine silt, clay diamicton, sand and gravel, and a loamy diamicton. Auger borings of another ice-walled lake plain only recovered diamicton. Both subglacial and supraglacial processes may explain ice-walled lake plain formation. The lower Maumee strandline mapped by Forsyth (1959) and Anderson (2011) has an elevation more consistent with the middle stand at 238 m and its morphology and sediment architecture suggest the Winameg Ridge is a spit. Pebbly sand collected from the ridge yielded an OSL age of 16.8 +/- 1.1 ka overlapping with the previously documented timing of Lake Maumee, but is not precise enough to differentiate among stands. This project provides a framework for several ongoing studies in the region and emphasizes the need for better chronology and surficial mapping.