Isaac Owen and Gwen Hughes Owen were married in Aberdovy North Wales during the 1850s. Isaac's brother Evan and Gwen's sister Elizabeth were married at the same time.
Isaac & Gwen lived in a stone cottage in Croisser Wales, where Isaac was a lay minister at the Presbyterian chapel. They had two children: Hugh H. Owen and Winnifred Owen. They sold the stone cottage to the David Wark Griffeth family when they emigrated to America.
They arrived in Vermont, where Isaac began his work in the marble quarries, and they later moved to Granite Maryland where Isaac was killed (as noted by the other poster).
Isaac and Gwen's gravestones were made by their son Hugh H. Owen, who also cut the cornerstone for the Congressional Library in Washington DC. Hugh later became a Presbyterian Minister, and is buried at the Trenton Cemetery in Pierce County Wisconsin.
Their daughter Winnifred is buried near them, at the Granite Presbyterian Church.
BTW, Evan and Elizabeth Owen also emigrated to America, and their son Hugh E. Owen married Isaac & Gwen's daughter Winnifred. Gwen and Evan were later married, after each had been widowed.
Source: family history document by Mary Gwen Owen [Swanson] (daughter of Hugh H. Owen) dated 9/27/1980