Some fossil forms have a short stratigraphic range, some long, some ranges
get extended by new finds. Some are clearly reworked. There have been
claims of "out of order fossils" that were later well-explained by
overthrust faulting.
What would "out of order" fossils mean?
>Karen: The concept of hundreds of millions of years is another matter! It's
>based upon the premise that much sedimentation indicates much time, and
>upon isotope ratios interpreted with that firmly in mind. Other
>interpretations of the isotope ratios, invoked when the dates don't fit the
>accepted timescale, may also apply when they do.
>
>Please explain, the enormous evidence pointing to an old earth especially
>from the radiometric dating makes a young earth hard to support. What
>"other interpretations" of these ratios are there ?
When the isotope ratios indicate dates that do not match the accepted
timeframe (such as K-Ar ratios that "date" older than the accepted age of
the earth), alternate explanations for the observed ratios are explained.
The explanations are reasonable, having to do with realistic processes that
I would think could equally apply to the "accepted" dates as well. These
include, for example:
1. Fractionalization in the magma chamber
Argon (a gas) tends to rise and the K sink in a magma chamber, so that when
eruption occurs, the first layers of lava have more Ar (indistinguishable
from the expected radiogenic Ar), the later ones more K, exaggerating the
span of ages. This is a real problem, causing even historically dated
recent flows to give ancient dates -- explained by "incomplete degassing".
Also U sinks in the magma chamber more than Pb, so the first erupted layers
have more Pb....
2. Mixing lines
An "isochron" is really a mixing line. If the date (from the slope of the
line) is in the acceptable range, it is accepted. If it isn't,
contamination or change of initial isotope ratios is assumed. Ions can
migrate, even in a crystal (for example Rb and Sr ions). Samples from
different parts give different ratios. Mixing lines show the mixing, not
necessarily accurate time.
3. Additions to the magma chamber
Surrounding rocks melt and contribute their mix of isotopes to the magma.
The mixture changes continually. The changes reflect the characteristics
of the added materials, not necessarily only age.
Also, later heat and pressure (metamorphism) changes isotope ratios and
distribution.
So it is understandable that there are many unacceptable "dates" that have
to be thrown out. What I question is the assumption that the ones that fit
the accepted timescale are free of these problems, and therefore accurate.
It seems circular to me to accept isotope ratios as accurate only if they
fit the expected date range.
>
>If sedimentation was very rapid, the geological record does not represent
>much time.
>
>True, but that is contradicted by much of the evidence.
>
Or interpretations of the evidence.
>Karen: With rapid sedimentation, There's no need for multiple creation events.
>
>
>Only more miracles to explain away the reality.
Or being more realistic about the "reality"!