Elephant Rocks State Park

The granite here is around 1.5 billion years old, part of the St Francois Mountains, which are among the oldest exposed rock in the American midcontinent and stood as islands in a Palaeozoic sea. Groundwater working along joints rounded the blocks underground before erosion stripped the cover, leaving them stacked on the surface - the largest, Dumbo, is around seven metres tall and estimated at over six hundred tonnes. A one-mile paved interpretive trail circles the main formation and was among the first in the country designed for wheelchair and visually impaired access, with a braille guide. An abandoned quarry on the site supplied granite for paving and buildings including the Eads Bridge in St Louis, and quarry workers' graffiti from the 1800s is carved into the rock.

What's there

• Rounded granite boulders - weathered underground, then exposed.
• Dumbo at about seven metres - over six hundred tonnes.
• A paved braille trail - among the first accessible trails in the country.
• Quarry workers' carved graffiti - from the nineteenth century.

When to go

April to October. Two hours.

Practical notes

It is small - the loop takes about an hour. Climbing on the boulders is permitted. Summer heat on bare granite is heavy. There is little else immediately nearby.

Nearby

Johnson's Shut-Ins is south; Taum Sauk, the state high point, is close.

Key facts