The plates dive at 25-45 degrees? Continents don't get scraped off the plates? We are talking millions and billions of years here, are we not?It would help a great deal if you would just read up on the topic.
Yes but as continental rock is lighter than oceanic rock it's the oceanic plates than are most likely to be subducted not the continents.
Many mountain ranges were formed by two tectonic plates crashing into each other.
The Himalayas were formed by India (which was an island) crashing into Asia forcing the seabed up into mountains. So what was Oceanic crust is now part of the Asian continent.
Because those fossil beds are no longer on top of oceanic crust but part of the continental crust.
Magma can only be dated from the last time it solidified.
Very nice about those mountain ranges. How old are they? BTW, part of them is sedimentary rock.
Your crust has been recycled at least a few times at present rates, along with anything that was on the top of it. The crust and lithosphere float on a plastic. It is broken. You have tidal forces among many others working on those broken pieces. Anything you have now can go no further back than the last time that crust rose up and what collected on it since. How many millions of years was that?