This collection contains materials created and collected by Ian A. Smith, an employee of the California Portland Cement Company's Colton Plant from 1952-1977, as he researched the history of mining operations conducted at Mount Slover in Colton, California. The collection primarily focuses on the California Portland Cement Company's mining operations at Mount Slover, but also contains materials regarding Isaac Slover and the history of the southwestern United States, particularly that of San Bernardino County, California. Two versions of Smith's manuscript, "Vanishing Mountain: A History of Mining Operations at Mt. Slover, Colton, California", are included. Additionally, the collection includes photographs, notes, correspondence, press clippings, maps, and other material related to Smith's research.