Carbon 14 has a half life of 5,730 years. Scientists measure how much carbon 14 the rock has. For objects older than 50,000 years, scientists will test the age of the things surrounding it.
Therapeutic cloning Is the answer you’re looking for
I believe the answer is a Meander. (beware that this is actually a geography question not a biology one, please put it in the right section next time and it will be answered quicker!)