The Grand Canyon Welcome! You are encouraged to register with the site and login (for free). When you register, you support the site and your question history is saved.The Grand Canyon, which was previously thought to have been carved out by the Colorado river, was eroded away by a lava flow, according to a newer theory, took on its current form at an earlier date 6 to 7 million years ago. which was previously thought to have been carved out by the Colorado river, was eroded away by a lava flow, according to a newer theory, previously thought to have been carved out by the Colorado river eroded away by a lava flow, according to a newer theory, and previously thought to have been carved out by the Colorado river, was eroded away by a lava flow, according to a newer theory, and previously thought to have been carved out by the Colorado river, according to a newer theory, it eroded away by a lava flow and previously thought to have been carved out by the Colorado river, according to a newer theory, which was eroded away by a lava flow and Review Answer