Niagara Gorge is an 11-kilometre canyon carved by the Niagara River along the Ontario–New York border, stretching from the base of Niagara Falls to near Queenston. It marks the long retreat of the falls from their original position about 12,500 years ago, as the river eroded softer rock beneath the hard Lockport dolomite and steadily forced the falls upstream toward Lake Erie. The gorge’s powerful current and rapids have made it both renowned and hazardous, limiting passage to rare expert attempts and commercial jetboat tours. It also became the site of tragedy in 1883, when English Channel swimmer Matthew Webb drowned there.