12-07-2013, 08:53 AM
dakine and anyone else interested: here's a paper about the ages of the islands, including actual dates (based on radioactive decay dating) and calculated dates (based on subsidence modelling), and estimated maximum height (these are all dates above water; as geochem said, a lot of time is spent getting up from the seafloor). The maximum size above water can be determined by the steep drop off that occurs where lava hits the ocean compared to the flatter flows on land.
https://drive.google.com/file/d/0B9Ytj7j...M4c2Z4U0E/
The maximum anything could have been evolving in the islands is about 30 million years, because between Kure and the previous island there was a gap where no islands were above water, except possibly small atolls. Also, between Kauai and Gardner (which was once about the same size as the Big Island, probably why it's still a bit above water today), the islands were small and didn't last very long before sinking and becoming like Kahoolawe. So to get to Kauai from the previous island with wet forest (Gardner) was a big jump, and not many things made it. There are only a few native plant or animal groups that are older than Kauai, namely the pomace flies (Drosophila), damselflies, and lobelioids (oha wai). The Drosophila are the oldest, at about 22-25 million years.
https://drive.google.com/file/d/0B9Ytj7j...M4c2Z4U0E/
The maximum anything could have been evolving in the islands is about 30 million years, because between Kure and the previous island there was a gap where no islands were above water, except possibly small atolls. Also, between Kauai and Gardner (which was once about the same size as the Big Island, probably why it's still a bit above water today), the islands were small and didn't last very long before sinking and becoming like Kahoolawe. So to get to Kauai from the previous island with wet forest (Gardner) was a big jump, and not many things made it. There are only a few native plant or animal groups that are older than Kauai, namely the pomace flies (Drosophila), damselflies, and lobelioids (oha wai). The Drosophila are the oldest, at about 22-25 million years.