[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Iridium near fossils?
William Blair schrieb:
> Assuming, as I do, that the impact theory of dinosaur extinction is
> correct, I'd expect the layers in which dinosaur fossils are found
> to be enriched with the iridium from the asteroid that killed them.
> Has this been found to be the case?
Hello William, hello List,
Yes, the K-T boundary layer (deposited within 200 years) after the
impact of the asteroid (10-15 km / 6-10 miles in diameter) that killed
the dinosaurs, is dramatically enriched in iridium. Dinosaur skeletons
are found in the strata underlying the boundary layer (which became
their "death blanket"). Absolutely no dinosaurs are to be found in the
overlying strata!
1) There is a 30-fold increase in iridium concentration in a thin layer
of clay that separates the highest Cretaceous and the lowest Tertiary
limestone beds near Gubbio, Italy.
2) On a sea cliff south of Copenhagen, Denmark, the thin layer of clay
marking the K-T transition, shows a 160-fold enhancement of iridium.
3) Another K-T boundary site, in New Zealand, is also marked by a large
Ir anomaly. The boundary clay is approximately 1 cm thick and the Ir and
C abundances rise sharply, by around 50x (Ir) and 250x (C) at the
boundary relative to the preceding 20 cm interval.
Best regards from Germany,
Bernd
----------
Archives located at:
http://www.meteoritecentral.com/list_best.html
For help, FAQ's and sub. info. visit:
http://www.meteoritecentral.com/mailing_list.html
----------
Follow-Ups:
References: