Onomonee Road Beach: Charlevoix Stone & Stromatolite Rockhounding in Leelanau County, Michigan

Plan your visit

Generally open to casual rockhounding

County

Leelanau County

State

Michigan

Postcode

49674

Coordinates

45.11297, -85.67549

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.

Best time to visit Onomonee Road Beach

Comfortable months (45 to 90°F highs)

Best months: April to November. Typical highs run 76°F in midsummer and 29°F in midwinter, with winter lows near 19°F.

Climate normals: NOAA 1991-2020 monthlies, NORTHPORT 2W station (2 mi away), adjusted for elevation.

Geology at Onomonee Road Beach

This spot sits on Traverse Group, mapped as limestone that formed roughly 395 to 385 million years ago. Limestone like this typically forms in ancient seas, so marine fossils such as brachiopods, corals, and crinoids tend to weather out of fresh exposures.

Mapped unit

Traverse Group

Age

395–385 Ma (Middle Devonian)

Rock types

limestone

Elevation

590 ft

Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.

Sources & verification

Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.

State guidance last verified: April 1, 2026

• Michigan DNR, Rockhounding rules
• Michigan Geological Survey
• Isle Royale National Park, Rules
• Community submissions reviewed against published agency rules