K-T Boundary Clay. |Sample Image | Spin Video | QuickTimeVR
Rotation| |K-T Boundary Clay.| The K-T boundary clay is is found
in thin layers all over the world at sedimentary levels that
indicate it is the same age everywhere: About 65 million years
ago. This is the boundary between the Cretaceous (K for some
reason) and the Tertiary (T for obvious reasons) periods, and
also the time at which there was a mass extinction. That such a
thin layer of similar material should be found all over the
globe is strange, but what's even stranger is that it is always
highly enriched in iridium compared everything around it. It's
as if something dumped a huge quantity of iridium on the earth
and spread it around in some kind of giant explosion. That
something was almost certainly a large (ca. 10km diameter)
chondritic meteorite, a type known to contain very high levels
of iridium compared to the earths crust. All the evidence points
to such an object hitting the Yucatan peninsula of Mexico a the
same time the clay was depos