Of, pertaining to, or of the nature of a cataclysm.

Of or pertaining to cataclysmists; holding the doctrine of violent upheavals: as, the cataclysmal school of geologists.

adjective. Of or pertaining to a cataclysm.

adjective. As destructive as a cataclysm.

adjective. severely destructive

"The belief belongs to what may be called the cataclysmal theory of progress, which improves the world by sudden starts, and clings so fondly to liquor-laws, and has profound faith in specific remedies for moral and political diseases."

cataclysmic  destructive  

cataclysmic