Sorry Sherryll, but he must have contacted me by email that I no longer have, and I don't recall details. Here's someone who shows Clark died 1880 in Benton County, but when the Corps of Engineers moved his wife Nancy's grave from Hogles Creek to Shawnee Cemetery at Warsaw, no marker for Clark was found:
http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=GET&db=3162616&id=I16824