On February 26, 1919, Congress passed the act that established the Grand Canyon National Park in the state of Arizona. But what created the canyon?
On February 26, 1919, Congress passed the act that established the Grand Canyon National Park in the state of Arizona. But what created the canyon?
西元1919年2月26日，国会立法通过在亚利桑纳州设立大峡谷国家公园。但是大峡谷是怎麽形成的呢？