The NY Times has an article by Sandra Blakeslee describing geological evidence for recent (i.e. Holocene) megatsunamis:
The explanation is obvious to some scientists. A large asteroid or comet, the kind that could kill a quarter of the world's population, smashed into the Indian Ocean 4,800 years ago, producing a tsunami at least 600 feet high, about 13 times as big as the one that inundated Indonesia nearly two years ago. The wave carried the huge deposits of sediment to land.
It's set up as an opposition between these geologists (notably, Dallas Abbott) and astronomers, who don't think there are enough big space rocks to cause that many recent impacts.
And of course there is the requisite mythical flood connection:
Dr. Masse analyzed 175 flood myths from around the world, and tried to relate them to known and accurately dated natural events like solar eclipses and volcanic eruptions. Among other evidence, he said, 14 flood myths specifically mention a full solar eclipse, which could have been the one that occurred in May 2807 B.C.
(via Gene Expression)