“I didn’t want to let the cat out,” Mr. Smith told The Tennessean newspaper in 2002. “I wanted to keep it in the bag longer.”
Marion Otis Smith was born on Sept. 24, 1942, in Fairburn, Ga., the only child of Otis Smith, a farmer, and Bernice (Stephens) Smith, a homemaker. His parents later divorced, and he was mostly raised by his grandparents.
After receiving bachelor’s and master’s degrees in history from West Georgia College, he entered the Army and served two years in South Korea. He was discharged in 1969.
Back in Georgia, he spent several years working different jobs, the sort that paid little but asked little in return, allowing him to spend as much time as possible underground. Eventually he cleaned up, a bit, and in 1974 he was hired as an assistant editor at the University of Tennessee, charged with preparing the 16 volumes of President Andrew Johnson’s papers for publication. He retired in 2000.
With Ms. Jones, he finally bought his first home in the early 2000s, on a backcountry trail north of Chattanooga called Bone Cave Road. He was married once, but just briefly. Ms. Jones is his only immediate survivor.
Caves were his life, but exploring them was not his only passion. He was perhaps the world’s leading expert on the history of mining for saltpeter, a primary ingredient in gunpowder, which in the 19th century was often harvested from caves.
In the 2010s he joined with Joseph Douglas, a historian at Volunteer State Community College in Gallatin, Tenn., in a project to document the thousands of signatures left by Confederate and Union soldiers in Mammoth Cave, in central Kentucky. Mr. Smith was particularly taken with researching the men themselves, and he ultimately wrote about 80 miniature biographies.