have been from 500 years to 9,000 years, for example, because it is known that this river would have flooded and that the soil was moist (because the body was next to a river) and that a 9,000 year date would be ludicrous.
The reason is that the "scientific establishment" (the people who control the media, schools, etc.) wants to get the dates of fossils as old as possible to justify the theory of evolution and belittle those who believe in the Bible.
Radiometric dating (often called radioactive dating) is a way to find out how old something is.
The method compares the amount of a naturally occurring radioactive isotope and its decay products, in samples. It is the main way to learn the age of rocks and other geological features, including the age of the Earth itself.
Measurements should be taken on samples from different parts of the rock body.
This helps to counter the effects of heating and squeezing, which a rock may experience in its long history.
the area was covered by an ocean) suddenly or slowly became exposed to dry heat and became a desert.
it is dated based on where "Fossil B" fits on the phylogenetic tree relative to "Fossil A"). when an unstable parent atom becomes a stable daughter atom, the dating of the specimen can no longer be done accurately), dating of old fossils is generally impossible to do directly.
No matter when Kennewick Man died, his bones were exposed to the flooding of the Columbia River, plus the bones were exposed to rain, humidity, moisture in the soil (i.e.
water which came from the river through the soil), and so on.
With this in mind, if George and Mary had existed 100,000 years ago, it is safe to say that humans should have built the B-2 bomber 90,000 years ago (being generous, as always, to the theory of evolution).
As far as the evolution debate is concerned, this aspect of the debate is so complex and so affected by pre-conceived notions (such as the fact that many dinosaur fossils are dated according to their location on the phylogenetic tree), that for all practical purposes, dating techniques cannot be used as a proof for evolution or as a proof for creation science.