Glacial Grooves Geological Preserve
A 400-foot trough of parallel grooves exposes Devonian limestone, marine fossils, and the abrasive force of debris-laden ice on an island reached only by ferry, boat, or plane.
Artwork inspired by Dominick Labino
The grooves formed when continental ice and rock debris scoured relatively soft Columbus Limestone, leaving channels far larger than ordinary scratches. Quarrying later removed many island grooves but exposed and preserved this spectacular section, so industrial extraction is part of why the feature can be seen. Marine fossils in the bedrock add a much older Devonian sea beneath the Ice Age story.
Walk both sides of the fenced trough and compare groove direction, depth, polished surfaces, and broken fossil textures. The improved upper viewpoint provides accessible viewing, while stairs and footbridges reveal changing angles. The site is free, but reaching Kelleys Island requires ferry or other transport; check the last return trip before lingering at the north shore.
- Exposed length
- About 400 feet
- Bedrock
- Devonian Columbus Limestone
- Admission
- Free
Quick guide
- Follow groove direction
- Parallel channels record ice movement across the island.
- Find marine fossils
- The limestone began in a tropical sea hundreds of millions of years earlier.
How to see two vanished environments in one rock
- Follow groove direction
- Parallel channels record ice movement across the island.
- Find marine fossils
- The limestone began in a tropical sea hundreds of millions of years earlier.
- Include quarry history
- Extraction destroyed grooves elsewhere but exposed this section.
- Plan the ferry
- Island transport, not site admission, controls the visit.
Good to know
The preserve is on Kelleys Island, not at the mainland ferry dock. Ferry schedules, weather, vehicle lines and the last return sailing matter more than the short on-site walk.
Notice these
- Deep parallel grooves
- Marine fossils
- North-island alvar setting