What I'd really like to see on this thread is discussion of some very specific locations and formations and how they were assigned to particular time periods, actually rather than hypothetically. The question I had was really about how you determine at a given location whether and how the various layers represent the established time periods of the Geologic Time Table.
Well, that's what you've got. If you want the dumbed down version, it goes like this: Clever people
who have actually studied geology found it out for you, that's how you know.
Also, using the fossils as an indicator would seem to beg the question in some cases, since you have defined in advance that a particular kind of fossil only occurs at such and such a depth.
Not at all. Obviously fossils are only used as index fossils if it has been
discovered that, whenever they can be dated, they only occur in a certain period.
Clearly the age of a fossil cannot be a matter of
definition.
Edited by Dr Adequate, : No reason given.
™ Version 4.2
