Rocks & Minerals

The Geology of D.A.R. State Park, Mt. Philo State Forest Park, Sand Bar State Park

Gems in the Smithsonian Institution

The Geology of Button Bay State Park

The Geologic Story of Colorado National Monument

Fossil Forests of the Yellowstone National Park

Ancient Landscapes of the Grand Canyon Region

Texas Gemstones

The Book of the Pearl

The Geology of Mt. Mansfield State Forest

Earth Features and Their Meaning An Introduction to Geology for the Student and the General Reader

Notes on Collecting and Preserving Natural-History Objects

The Geology of Groton State Forest

Cave Regions of the Ozarks and Black Hills

Across Mongolian Plains

Underground Treasures: How and Where to Find Them

The Ornithosauria

A Short History of the Academy of Natural Sciences of Philadelphia

Devils Tower National Monument