# Interstate State Park Glacial Pothole Walk: geology field guide

Canonical page: https://lithomap.app/resources/field-trips/interstate-state-park-geology-wisconsin
Last access and rule review: September 18, 2026
Page purpose: Original LithoMap trip-planning reference for a protected or rules-limited geology destination where this guide authorizes no removal.

## Direct answer

A no-collection walk through the Dalles of the St. Croix, where basalt, glacial meltwater, and sediment abrasion produced a celebrated pothole landscape.

## Location and material

- State: Wisconsin
- Area: St. Croix Falls, Wisconsin
- Category: Geology observation
- Collection status: Observation only
- Expected material: Basalt bedrock, Glacial potholes, Meltwater gorge landforms

## Authorization

The Wisconsin DNR protects the Dalles State Natural Area inside the park and prohibits collecting rocks, minerals, fossils, soil, or other natural material there.

## Access

Check park admission, trail condition, interpretive-center hours, ice, flooding, and seasonal notices.

## Tools, limits, and season

- Tools: Camera, notebook, and binoculars only. Do not remove rock, enter potholes, climb closed faces, or move stones.
- Limits: Observation and photography only; all natural material remains in place.
- Season and current status: Trails are year-round but can be icy, wet, crowded, or closed; verify conditions.

## Conditions

- Collect nothing.
- Stay on designated trails and overlooks.
- Do not move or stack rocks.
- Respect all State Natural Area restrictions.

## Geology

Ancient basalt confines the St. Croix gorge, while powerful glacial meltwater drove sand and stones in vortices that bored cylindrical potholes.

The shape and location of each pothole record flow and abrasion, so the feature and its loose contents should remain undisturbed.

## Field plan

1. Open the current official source and check alerts before leaving home.
2. Confirm the property boundary, parking location, and activity rules on arrival.
3. Begin with observation or surface searching and make the smallest possible disturbance.
4. Photograph context before handling any material that the current rules allow you to keep.
5. Pack out every item you brought and leave protected or uncertain material in place.

## Safety

- Cliffs, stairs, ice, and the river require close attention.
- Stay behind barriers and keep children near adults.
- Wear traction appropriate to current conditions.

## Official sources

- Dalles geology and no-collection rules — Wisconsin Department of Natural Resources: https://dnr.wisconsin.gov/topic/statenaturalareas/DallesStCroixRiver
- Pothole Trail — Wisconsin Department of Natural Resources: https://dnr.wisconsin.gov/topic/parks/interstate/recreation/hiking

This guide is not a permit, reservation, boundary survey, legal opinion, guarantee of access, or promise of a find. Open every official source again before travel. Current signs, closures, permits, claim boundaries, and staff instructions control.