Editing Kelleys Island, Ohio (section)

===Geology===
Kelleys Island consists of Middle [[Devonian]] ([[Eifelian]] Stage) [[limestone]]s and [[Dolomite (rock)|dolomite]]s, the Lucas Dolostone, and the [[Columbus Limestone]]. The Lucas Dolostone is intensely dolomitized. With the exception of localized algal [[Reef knoll|mounds]] and [[Stromatoporoidea|stromatoporoids]], it is sparsely [[fossiliferous]]. Several species of stromatoporoids, which represent four [[genera]], have been recorded from the Lucas Dolostone of Kelleys Island. The Lucas Dolostone accumulated within coastal [[subtidal]] to [[Intertidal zone|peritidal]] [[mudflat]]s. These mudflats were permanently submerged and progressively buried beneath muddy [[shoal]] and [[lagoon]]al [[sediment]]s as [[relative sea level]] rose and the shoreline shifted westward during the Eifelian Stage.<ref name="FeldmannOthers1987a">Feldmann, R.M., and Bjerstedt, T.W., 1987. [https://www.researchgate.net/publication/306106342_Kelleys_Island_Giant_Glacial_Grooves_and_Devonian_Shelf_Carbonates_in_North-Central_Ohio ''Kelleys Island: Giant glacial grooves and Devonian shelf carbonates.''] In Biggs, D.L., ed., ''Centennial Field Guide Volume 3 - North-Central Section of the Geological Society of America.'' Geological Society of America, Boulder, Colorado, p. 395-398.</ref>
[[File:Columbus LS etched KellysIsland.jpg|thumb|left|Etched section of hand sample of Columbus Limestone from quarry on Kelley's Island. Circular feature is cross section of a [[rugose coral]].]]

Overlying the Lucas Dolostone, is the Columbus Limestone, which consists of the lowermost Bellepoint Member, middle Marblehead Member, and uppermost Venice Member. The Bellepoint Member consists of [[wackestone]]s and [[packstone]]s, which accumulated as muddy shoals and contain a large number of [[rugose coral]]s, [[gastropod]]s, [[rostroconch]]s, and [[brachiopod]]s. The Marblehead Member consists of a lower, thick-bedded, [[chert]]y, dolomitic, heavily-burrowed [[mudstone]] deposited in lagoonal conditions below mean [[wave base]]. These mudstones grade upward into thinner bedded, sparsely fossiliferous packstones and grainstones of this member's upper part that accumulated as subtidal shoals. A rippled, [[hardground]] surface forms the top of the Marblehead Member This hardground represents either a period of subaerial erosion or the lack of sediment accumulation at a shallow depth for a significant interval of time. The Marblehead Member is overlain by mudstones and wackestones of the uppermost Venice Member of the Columbus Limestone. This member accumulated below wave base in the open sea after relative sea level rose again.<ref name="FeldmannOthers1987a"/>

The Devonian limestone and dolomite that comprise Kelleys Island has been deeply eroded and scoured by the [[Laurentide Ice Sheet]] over the [[Pleistocene]]. On the island, the largest exposure of [[glacial striations|glacial grooves and striations]] created by glacial erosion is preserved in Glacial Grooves State Memorial, which is associated with [[Kelleys Island State Park]]. Within the Memorial, giant glacial grooves in a depression about {{convert|9|m|ft|sp=us}} wide and {{convert|4.5|m|ft|sp=us}} deep are exposed in an [[outcrop]] about {{convert|120|m|ft|sp=us}} long. Near the east edge of the outcrop, a number of the grooves are relatively straight, smooth, and exhibit striated surfaces. Farther west, the path of the individual grooves becomes far more tortuous, and striations are less distinct and fewer in number.<ref name="FeldmannOthers1987a"/>

Munro-Stasiuk and others<ref name="Munro-StasiukOthers2005a">Munro-Stasiuk, M.J., Fisher, T.G. and Nitzsche, C.R., 2005. ''The origin of the western Lake Erie grooves, Ohio: implications for reconstructing the subglacial hydrology of the Great Lakes sector of the Laurentide Ice Sheet.'' ''Quaternary Science Reviews'', 24(22), pp.2392-2409.</ref> argue that the giant glacial grooves and the depression, in which they lie, were eroded by highly turbulent, high velocity, sediment-laden meltwater flows. Judging from similar tortuous, giant, glacial grooves, which are found all over, and between, the Lake Erie islands on high and low areas, the erosional features are interpreted to have formed during a subglacial meltwater megaflood that took place before or near the [[Last Glacial Maximum]].<ref name="Munro-StasiukOthers2005a"/>