July 1854
A town was laid out at the junction of Bass (Afton) creek with the Rock river
BeloitGrade A · 1 independent source
The evidence
“R., near the junction of Bass or Afton creek, with the Rock river. It was laid out in July 1854, by S. A.”
1856-history-of-rock-county/24-rock.md, PDF p. 164 / book p. 148
Guernsey, Orrin, and Josiah F. Willard, editors. History of Rock County, and Transactions of the Rock County Agricultural Society and Mechanics' Institute. Janesville, Wis.: William M. Doty & Brother, 1856. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871593.
Grade A: Found on a page of one of our sources