It began 600 million years ago with a broad shallow sea that covered much of the continent. For 100 million years rain, wind and waves ground rocks into powder that collected in the concave sea bottom atop the already ancient Pre-Cambrian rocks. Then the Earth shook, bringing forth the Appalachian Mountains. Rivers changed courses, intermingling, forming huge muddy deltas. Eons cemented that mud into the purple-red shale of the Queenston Formation.

The sea's warm tropical waters were home to tiny creatures that wove massive honeycombed reefs. When they died the water crushed their homes, using the ruins to form the caprock of the escarpments. Then that sea drained away and rivers etched patterns into the soft rock, forming basins that would become great inland seas. And the continent drifted north, dooming the world that existed.

The ice struck, four times in rapid succession, crushing what would not move, carving a new face for the world it covered. New rivers and seas replaced those that had gone before. Then the glaciers began to thaw, the melt flooding craters and ravines and forcing its way to the Atlantic Ocean. New life formed for this new world, while the old died away, unable to adapt.

This is Niagara Falls, one of the greatest wonders of the natural world.