| Title | Comment | Keywords |
|---|---|---|
| Past Deserts | 07:38 - 08:29 (00:51) / 1.6 MB | "Southwestern United States", desert, "fossil dune", "Grand Canyon", sandstone, "Zion National Park", "cross-bedding", oxidation, iron, "dry land", plant, animal, fossil, forest, "geologic time", "plate tectonics", orogeny, mountain, "rain shadow" |