ANTARCTICA was the only continent where extensive coal beds failed to form during the warm Cretaceous period between 150 and 65 million years ago. The lack of coal has long been a puzzle because the continent was heavily forested at the time. Now David Beerling of the University of Sheffield has developed a model that solves the puzzle (
He says high levels of carbon dioxide stimulated the growth of thick forest canopies, causing the water table to drop. "Because the vegetation was actively transpiring, it maintained the water balance close to zero over most of the continent, drawing water out of the soil," he says.
Coal begins to form in boggy ground, and the few places in Antarctica where thin seams of coal are found are in spots where Beerling's model predicts that some water will have accumulated.
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