Examine how telltale landforms that appear in a dry northwestern landscape are evidence that the area was once covered by a vast amount of flowing water, in this video from NOVA: Killer Floods. Vic Baker is in the Channeled Scablands, about a 200-mile drive east of Seattle, Washington. Pointing out some of the landscape’s more distinctive features, Baker explains that the horseshoe shapes of the cliffs in the Dry Falls Canyon, similar to what is seen when you look at Niagara Falls from overhead, are indicative of massive waterfalls. However, the Dry Falls Canyon is five times the span of Niagara Falls and twice as tall, which suggests that this formation used to be a truly enormous ancient waterfall. The valley floor contains another notable feature: giant potholes. Potholes are found along the bottom of fast-flowing rivers. Their presence suggests that a large ancient river once flowed here. This resource is part of the NOVA Collection.