"You have to figure out what is in the geological record" to draw any firm conclusions, Boslough says. From his models, an impact might produce the same kinds of surface manifestations attributed to superplumes: flood basalts, large changes in sea level, radically increased mechanical erosion that alters ocean water chemistry, and sediment deposits that indicate a global change has occurred.
But Abbott and Isley think there is hard evidence for impact-enhanced superplumes: certain types of rocks associated only with superplumes, say, or some kind of universal, physical characteristic in the earth consistent only with major plume events. For now, though, not enough evidence exists to indict superplumes as an extinction accomplice.
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