Washington : U.S. G.P.O. ; Denver, CO : For sale by U.S. Geological Survey, Information Services, 1998.
iv, 36 p. : ill., maps (some col.) ; 28 cm.
"A joint study conducted in collaboration with the Illinois State Geological Survey ... [et al.]."
Shipping list no.: 1998-0204-P.
One folded col. map in pocket.
Includes bibliographical references (p. 31-36).
Also available via Internet from the USGS Web site. Address as of 6/21/04: http://pubs.usgs.gov/bul/b2150b/b2150b.pdf (full text); http://pubs.usgs.gov/bul/b2150b/plate.html (plate 1 only); current access available via PURL.