Raymond Siever vs Robert Folk

Raymond Siever was an American geologist who spent his academic career at Harvard University as a professor of geology. He co-authored "Understanding Earth," a widely used introductory geology textbook, alongside John Grotzinger and Thomas H. Jordan. His research focused on sedimentary petrology, the chemistry of sediments, and diagenesis—the physical and chemical changes sediments undergo after d...

Robert L. Folk was an American sedimentologist and petrologist who taught at the University of Texas at Austin. He developed the Folk classification systems for both carbonate and siliciclastic sedimentary rocks, providing standard tools for geologists to describe rock composition and texture based on allochems, orthochems, and matrix. Later in his career, he researched nannobacteria and their rol...