Subtle relict channels associated with large dolines in an area formerly beneath the Laurentide Ice Sheet, northern Ohio, USA

Low‐relief dry channels are observed across the Bellevue‐Castalia Karst Plain of north‐central Ohio, USA. The area was repeatedly glaciated, and the channel forms are of interest because the linear pattern may be related to glacial processes. The 3–5 m deep channels are discontinuous, 0.15–0.4 km wide, and ~2–11 km long. Elongated large dolines of collapse/subsidence origin are parallel with ice flow, bedrock strike, fractures and joints, and are associated with the channels. There is no evidence of continued collapse since deglaciation. Smaller suffosion dolines developed within sediment are active and common across the landscape. Electrical resistivity tomography across uplands, channels, and large dolines indicates two units, a low‐resistivity till over a high‐resistivity limestone bedrock. Low‐relief ridges a few hundred metres long are within, and parallel to, some channels, and are composed of bedrock with till veneer. Where till is exposed, it is tightly packed into dissolutionally enlarged fractures and cavities within bedrock, reducing groundwater connectivity into the subsurface. Channel orientations are offset and overlap with bedrock fractures, joints and elongated doline orientations. Three hypotheses are proposed to explain the channels. A subglacial meltwater channel hypothesis is supported by the channels incised into bedrock, covered in till and cross‐cut by deglacial shorelines. A linear arrangement of collapse dolines hypothesis is supported by many channels orientated parallel to fractures within the bedrock and a crenulated channel margin. A fluviokarst origin for some channels relies upon preglacial subaerial streams progressively captured within Columbus Limestone bedrock, and subsequent non‐selective glacial erosion. Erosion during the last glaciation may have been limited to ~1 m of bedrock, which would support preservation of karst features through successive glaciations. The second and third hypotheses are related, and with all three hypotheses these various previously unrecognized channels can be explained.