Rivers wind through earth, cutting down and eroding the soil for millions of years, creating a cavity in the ground 277 miles long, 18 miles wide and more an a mile deep known as the Grand Canyon. Home to an astonishing variety of plants and animals that have lived and evolved within its walls for millennia, the Grand Canyon is much more than just a hole in the ground. Follow a...(展开全部)

Rivers wind through earth, cutting down and eroding the soil for millions of years, creating a cavity in the ground 277 miles long, 18 miles wide and more an a mile deep known as the Grand Canyon. Home to an astonishing variety of plants and animals that have lived and evolved within its walls for millennia, the Grand Canyon is much more than just a hole in the ground. Follow a...(展开全部)

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[美]道格拉斯·S.梅西（Douglas S. Massey），普林斯顿大学社会学和公共事务系亨利 G.布莱恩特教授，普林斯顿大学人口研究办公室主任。 [美]兰·奥尔布赖特（Len Albright），东北大学社会学系助理教授。 [美]瑞贝卡·卡斯诺（Rebecca Casciano），瑞贝卡·卡斯诺有限责任公司首席执行官。 [美]伊丽莎白·德里克森（Elizabeth Derickson），普林斯顿大学社会学系博士候选人。 [美]大卫·N.肯锡（David N. Kinsey），普林斯顿大学伍德罗·威尔逊学院公共和国际事务专业讲师，Kinsey & Hand规划咨询公司的合伙人。