[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Iridium near fossils?
Thanks to all for the explanation of the K-T boundary layer.
I am aware that it seems to mark the date of extinction of the
dinosaurs. However, what I'd like to know is whether or not
any of the adjacent layers of earth or rock removed when large
dinosaur fossils are excavated have been found to be highly
enriched in iridium. In other words, proof of the impact theory
by direct association with a dead dinosaur rather than just by
the dating of a layer of rock.
Bernd Pauli wrote:
>
> 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
> ----------
----------
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
----------
References: