|
 This
is unique stromatolite called impact fallback breccia. Coming
from the Lower Ordovician, it is also very young, from a time
when stromatolitic reefs no longer dominated the planet's marginal
marine environments. Note the heterogeneous patterning with sharp
and angular fragments of various size embedded in the reddish
matrix. This beautiful pattern was formed during the so-called
Glover's Bluff meteorite strike during the Ordovician; a fragment
from the same meteor also struck in near Elm Rock Illinois, forming
a mile-wide crater. The meteor that struck what is now the Oneota
formation plowed through the stromatolite reef deep into the earth,
spewing molten rock upward, with everything eventually falling
back to earth, with one result being the "fallback impact
breccia" seen here. It seems certain that the living stromatolite
would have been decimated.
|
