The oldest information in general that has been passed on continuously are the oral stories in Australian Aborigine culture, known as Dream Time stories that accurately describe volcanic activity that occurred ~10,000 years old.

I don't know about that being the oldest. There are Native American stories in the northwest recounting huge, apocalyptic floods, which may very well be describing the Missoula Floods from 13,000 to 15,000 years ago. (It happened several times over the course of a few thousand years.)