Hawai'i Sinkhole to the Past

Geological data from a sinkhole cave on the island of Kauai in Hawai'i contains evidence of environmental change wrought by the human colonization of the island. Apparently there are no specific dates from the deposits yet, but they include evidence for at least one tsunami about the same time as the first human colonization (believed to have occurred about 300 AD).
Kaua'i cave tells 10,000-year tale - The Honolulu Advertiser