| Title | Comment | Keywords |
|---|---|---|
| An Oxygen Rich Atmosphere | 19:17 - 19:54 (00:37) / 1.3 MB | "blue-green algae", cyanobacteria, oxygen, atmosphere |
| Change in Environmental Conditions | 04:59 - 06:49 (01:50) / 2.8 MB | "Stanley Aramic", fossil, "Alexander Hills", "Eastern California", stromatolite, "sedimentary rock", environment, sand, cyanobacteria, "rate of sedimentation", deposition, precipitation, "calcium carbonate", "Crystal Spring Formation" |