He was a renowned paleobotanist working on the floras of the Late Cretaceous and Paleogene.
[1] Probably his best known research today are comprehensive articles and papers about the Yellowstone Petrified Forest where he reported the presence of conglomerates from stream deposits, breccias from mudflows or landslides, volcanic tuff from the numerous volcanic events, and lava beds.
[1][2] Dorf theorized that these specimens do not merely represent one entombed forest but rather include trees from 27 separate forests (the most in the world), each stacked on top of the other, layer by layer, to a thickness of 1,200 feet (370 m).
During the ensuing dormancy, new trees grew up on top of the old, only to be encased by the next volcanic activity.
[citation needed] The name of the monotypic eurypterid genus Dorfopterus from the Devonian of Wyoming, in the United States, also honors Dorf.