SCEC INSTANeT
News
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SCEC INSTANeT
News |
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By Chris Sorlien I'd been doing field work on Santa Cruz Island, off the coast of California, originally measuring the scratches and grooves on fault surfaces that record slip of past earthquakes. Santa Cruz Island is part of a large fold that includes the Santa Monica Mountains. (A "fold mountain" is usually a product of deformation -- mountains that have been formed by the large-scale folding and later uplift and deep erosion of stratified rocks.) During the low sea levels of the last glacial maximum at 18,000 years ago, Santa Cruz Island and neighboring islands were joined, but there was still a 6 km water crossing between the islands and the mainland. Only a few mammals reached the Islands -- today, these include only skunks, bats, foxes, feral sheep and pigs, a few horses, and mice. Mammoths had also swum to the Islands, but restricted food supplies eventually affected their size: they became the oxymoronic shoulder-high pygmy mammoths. It has been presumed that these became extinct sometime after Native Americans arrived on the islands more than 13,000 years ago. Marc Kamerling (UC Santa Barbara, Institute for Crustal Studies) and I were out for a few days investigating lava flows within the stack of Miocene volcanic debris, faults, and ancient marine surfaces uplifted during countless earthquakes. We found ourselves walking along the cliffs along the northeast tip of the island. Looking down, we spotted a small hole in the ground that appeared to be collapsed skylight to a tunnel. Suddenly, we were aware of a brownish, shaggy, furry mammal about the size and shape of a badger (which are not known from the Island) scurrying past us and into the tunnel. Marc and I looked at each other and may have said simultaneously "What was that?" If it had to be one of the island's mammals I might have said it was a fox; but we had seen plenty of these at close range, and this elusive creature's fur was far too thick and long. It was also the wrong shape. Since our "sighting," I fantasize that the mammoths did not go extinct, but instead continued to converge on the ideal island ecosystem body size: the breadbox. The breadbox, you ask? Well, yes -- there is also an extinct giant mouse from the island. I surmise that, to protect themselves from changing climate and the increasing human population, our imaginary (?) "breadbox mammoths" found refuge underground, where they roam today. |
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