The four northern Channel Islands off California, including Santa Rosa Island, were conjoined during the last ice age into Santa Rosae, a single island that was only five miles (eight kilometers) off the coast.
Geography took its present shape after the continental ice sheets melted and sea levels rose one hundred and twenty meters.
There is also evidence to suggest that a submerged island, Calafia, lay between Santa Rosae and the mainland.
A thirteen thousand-year-old skeleton—the Arlington Springs Man—found on Santa Rosa island demonstrates that the earliest Paleo-Indians had watercraft capable of crossing the Santa Barbara Channel, and lends credence as well to a "coastal migration" theory for the peopling of the Americas.
This is the oldest set of human remains yet found in North America.
Pygmy mammoths (Mammuthus exilis), which became extinct more than ten thousand years ago, have also been excavated here.
