A while ago, I got to wondering how geology was depicted in stamps. I found this website which showcases some U.S. contributions to the theme of "rocks and fossils" in stamps. There's a good variety, ranging from geological features in national parks (like the Devil's Tower image at left) to mineral ores, to dinosaur fossils, to a stylized set depicting energy resources for the 1982 World's Fair in Knoxville, Tennessee. Below right is the stamp for "Fossil Fuels." I like how it has both a fern (swamp flora, source of coal) and a trilobite in the same inky-black seam. This is an odd choice.

Why? First off, trilobites are marine arthropods, characteristic of the Paleozoic era, and they are not thought to be a major source of hydrocarbons. (Other marine organisms called phytoplankton are thought to be the main source of petroleum deposits.) Second, these two organisms (the terrestrial fern and the marine trilobite) are very unlikely to end up in the same geologic deposit: sedimentary layers are either terrestrial or marine, but rarely a combination of both. The stamp is charming in its geological inaccuracy, eh? I like it.

Another website, maintained by the Unversity of Buffalo (NY) Libraries, shows geological stamps from around the world.