Fallen Rock Pillar

Pillar Rock is a pillar-like monolith in the Columbia River, near its mouth in the state of Washington. Originally rising 75-100 feet, it was dynamited and reduced in height to about 25 feet above the water to serve as a navigational aid and light. The Lewis and Clark Expedition camped twice near the rock, on November 7 and November 25, 1805.
Data from: en.wikipedia.org