Geology of the Sudbury Impact Layer, Minnesota, Guidebook

The PDF version of a field trip guidebook about the geology of 
the Sudbury Impact Layer within Minnesota is available online. 

It is:

Jirsa, M., and P. Fralick. 2010, Field Trip 4: Geology of the 
Gunflint Iron Formation and the Sudbury Impact Layer.
in J. D. Miller, ed., pp. 77-92. Field Guide to the Geology of 
Precambrian Iron Formations in the Western Lake Superior 
Region, Minnesota and Michigan. Guidebook no. 10-01,
Precambrian Research Center, University of Minnesota Duluth.

PDF file at:
http://www.d.umn.edu/prc/workshops/Guidebooks/BIF%20Guidebook4.pdf
and http://www.d.umn.edu/prc/workshops/Guidebooks.html

Also, there is:

Jirsa, M., and P. Fralick. 2011, The Sudbury Impact Layer in 
the Western Lake Superior Region. Geological Society of 
America Abstracts with Programs, Vol. 43, No. 5, p. 187.
http://gsa.confex.com/gsa/2011AM/finalprogram/abstract_194565.htm
http://gsa.confex.com/gsa/2011AM/finalprogram/session_28353.htm

Best wishes,

Paul H.