Portrait of McBride at approximately 47 years old holding a slab of Caballos Novaculite.

Portrait of Busch at approximately 60 years old.

Portrait of Busch at approximately 60 years old.

Portrait of Bostrom at approximately 50 years old.

Portrait of Blaisdell at approximately 45 years old.

Portrait of Bickert at approximately 55 years old.

Portrait of Bickert at approximately 55 years old.

Candid photograph of Pettijohn in the field using a magnifying lens to examine a rock specimen.