The collection contains correspondence, typescripts and scientific articles related to biological and archaeological expeditions that Dr. Loomis made to Patagonia, South America, 1911-1912; the Big Badlands in South Dakota; the Wasatch Basin in Wyoming; Converse County in Wyoming; Sioux County in Nebraska; and other expeditions to Maine, Colorado, Arizona, New Mexico, and Florida.

This collection is organized into five series:

• 1. Correspondence
• 2. Typescripts
• 3. Printed Articles by Loomis, 1901-1936
• 4. Newspaper Clippings
• 5. Miscellaneous (notes, student papers and clippings)