On I-90 Frontage Road, 1.1 miles east of Bear Gulch Road, on the right when traveling west.
About 350 million years ago, much of Montana was submerged under a shallow sea. Billions of tiny marine creatures thrived in the water and when they died their bodies settled into the muck on the sea bed. After hundreds of millions of years of . . . — — Map (db m71505) HM
On Rattler Gulch Road, 2.1 miles north of I-90 Frontage Road, on the right when traveling north.
The limestone feature (outcrop), located across the road, known as the Madison Limestone Formation, was deposited about 350 million years ago in a shallow sea. It was uplifted about 65 million years ago during the Laramide Orogeny (when the Rocky . . . — — Map (db m80318) HM