Wolves are changing not only the wildlife of Yellowstone National Park since being reintroduced after a 70-year absence, but also the geography—namely, the rivers.

This stunning video narrated by investigative journalist George Monbiot illustrates the "trophic cascade" effect that wolves have had on the very geography of Yellowstone. Two studies by researchers at  Oregon State University in the past couple of years have documented the transformation of wildlife as a result of the resurgence of the wolf at Yellowstone.

RELATED: Wolves of Yellowstone Feasting On Elk; Good News for Bears & Berries

The video below goes a step further than the OSU studies did, transforming that academic documentation into actual images.

“As soon as the wolves arrived they began to have the most remarkable effect,” Monbiot says of their reintroduction in 1995.

Without wolves, he points out, elk (referred to as deer in the video, which is short for red deer, the British term for elk) used to decimate the vegetation. When the wolves came, even though there were few of them, the elk changed their behavior, steering clear of valleys and gorges. The vegetation came back, and with it the trees, then the birds. Beavers came too, since they now had trees to eat and work with, and that created habitat for other small mammals. And so it went, with berries proliferating, which helped the bears thrive, animals that in turn helped prune the elk population by eating calves.

“But here it gets even more interesting,” Monbiot says. “The wolves changed the behavior of the rivers.”

Watch the video to find out how—and to be wonderstruck, as if Indigenous Peoples needed any reminders, of how interconnected everything is, in ways we cannot imagine.