'Circumstantial evidence'
The researchers would also repeat carbon dating on cores to verify ages, said Dr Goodbred, but he has a hunch the tsunami theory will win out.
"We're building a case of circumstantial evidence that is getting harder and harder to ignore," he said.
While many geologists say a submarine landslide is the likely trigger of a tsunami, a group led by Columbia University geologist Dallas Abbot thinks a space impactor may have set off the massive wave.
Some researchers suspect
a space impactor may have
been involved
Her team discovered material in the New Jersey and Hudson River cores dated to 2,300 ago, and believe it to be meteoritic in nature. This includes carbon spherules, shocked minerals, and nanodiamonds, which are produced under extreme pressures and temperatures.
"We didn't find the typical shocked quartz, but that is usual for a water impact," said Dr Abbott.
She theorised that an asteroid landed in the water off the coast of New York and New Jersey, either creating the wave directly or triggering a submarine landslide. No crater has yet been found.
Many geologists and other scientists remain sceptical of the asteroid evidence so far; but proof of an asteroid impact is not necessary to build the case for a massive wave.
As Dr Goodbred pointed out: "The tsunami story stands on its own without the impact."
