If you’re following the Ken Burn’s documentary “Country Music,” you’ll have heard about the Bristol recordings. In 1927 Ralph Peer, with the Victor Talking Machine Co., set up a temporary music studio in Bristol, Va., to record Appalachian musicians and their songs. The best-known artists emerging from the sessions are Jimmie Rodgers and the Carter Family. Rusty Nail will explore the Bristol recordings, pairing an original recording with a more contemporary cover of that same song. One cover featured in this week's program includes Boz Scaggs with Duane Allman on guitar. The show will open with two songs highlighting families living and working in coal country. Not often associated with country music, Natalie Merchant contributes to the coal country song list, and provides beautiful and haunting vocals.