for in his days was the earth divided

Genesis 10:25 reads:

And unto Eber were born two sons: the name of one [was] Peleg; for in his days was the earth divided; and his brother's name [was] Joktan.

I used to think that this verse had something to do with continental drift. However Dr. John Morris of ICR points out in "What Happened in the Days of Peleg?" that

while continental separation is well supported, it is still unproven, and very likely unprovable ... The traditional interpretation relates Peleg's day to the division of language/family groups at the Tower of Babel.