Wisconsin. Chief Geologist / Geology of Wisconsin. Survey of 1873-1879 ...
Volume II (1877)
[Chapter IV. The lower Silurian rocks], pp. [unnumbered]-607 PDF (31.6 MB)
Based on date of publication, this material is presumed to be in the public domain.| For information on re-use see: http://digital.library.wisc.edu/1711.dl/Copyright