Dewey McLean is a geologist who crusaded on behalf of volcanoes and lostthe Great Dinosaur Extinction Debate against Luis Alvarez.
Dewey proposes that the Deccan Traps in India spewed lava for hundreds of thousands of years until they finally managed to kill off the dinosaurs. In a nutshell, Mountain Dewey proposes for the Cretaceous what his British counterpart Paul Wignall proposes for the Permian: that volcanoes are the agents that Mother Nature uses to produce mass extinctions. This nonsense is easily debunked here.
It is this dangerous position of his is what brought him head to head with Luis Alvarez who was enthusiastically peddling his amusing asteroid theory at the time. This is a fight for which both of them will be remembered more than for the nonsense of volcanism or asteroids as agents of extinction. A Volcanists also fail to explain the physical mechanism of how gases and a rarified or toxic atmosphere leave certain animals alive. Dewey does it in reverse. He assumes that the defunct species could not tolerate the sudden change and that those that survived apparently could. This is merely a DESCRIPTION. He doesn't EXPLAIN by what physical mechanism it happened.
, of course, becomes the Achilles Heel of his theory. Without an explanation, without a mechanism that can explain step by step the physical cause, he is left with magic.