Francis J. Pettijohn

Francis J. Pettijohn was an influential American geologist known for his significant contributions to sedimentary petrology. His work, particularly his classifications of sedimentary rocks, forms the basis for modern discussions in the field.

Pettijohn, along with Robert R. Shrock and Paul D. Krynine, published seminal articles in 1948 that advanced the understanding and classification of clastic and nonclastic rocks. His classifications, especially for sandstones, emphasize texture and mineralogy, providing a framework for interpreting depositional settings and source areas. His research helped geologists understand how rocks like sandstones are formed and classified, contributing to the deciphering of Earth's history.123