1850 my ago, there was a huge impact crater formed at Sudbury, Ontario, 500 km E of Negaunee.  This was a huge meteorite, similar to the Hadean bombardment, although it happened in the Archean. This great event seems to have ended the period of banded iron formation.

This boulder was transported from near Marquette (See map below) to the Michigan Tech Campus so that our university could view and enjoy this unusual rock, a spectacular impact breccia associated with a huge meteorite which triggered magmatism from the deep earth and the formation of nickel sulfide deposits.  It is also the apparent cause of the end of a long period of banded iron formation in earth’s ocean basins and especially in the UP and Minnesota.  The breccia lies immediately on top of the iron formations and is marked by fragments of all sorts of rocks which were found on the surface near Sudbury 1850 my ago.