Letters The Keweenawan System By M. E. Wadsworth See allHide authors and affiliations Science 30 Sep 1887:Vol. ns-10, Issue 243, pp. 166DOI: 10.1126/science.ns-10.243.166 M. E. Wadsworth Find this author on Google Scholar Find this author on PubMed Search for this author on this site Article Info & Metrics eLetters PDF This is a PDF-only article. The first page of the PDF of this article appears above.