According to the records I have been able to locate so far Isaiah Clark was born in Penobscot County, Maine around 1806. Based on records, it appears his father was Jephtha / Jeptha Clark. The family moved to Ohio between 1810 and 1820.
I have records for Isaiah once he moved to Ohio including his marriage to Nancy Ann Bailey, the births of most of his children, his service in the Civil War, and his death.
I have found Jephtha / Jeptha in Penobscot, ME in 1810 and in Washington, OH in 1820, 1830, and 1840. I have not found any record of him after 1840.