English: Here lava from the Uinkaret volcanic field slops down into the Grand Canyon from its north rim. On the right is Lava Falls, with Vulcan's Throne at the top. The throne is about 73,000 years old. These are among the most recent features of the Grand Canyon. The topmost or newest layers over which the lava flowed — Kaibab Limestone — was laid down in early Permian time, around 290 million years ago. All the rocks below are older, on down to the Vishnu group at the bottom of the canyon, around 1.7 billion years old.