Miles of sediment—rocks pummeled and weathered into glassy sands and dense clays—are piled fat on top of the bedrock in places like the Mississippi Delta or Bengal Basin. In other areas, only a thin skin of dirt covers the hard bedrock. Occasionally, atop mountains or astride a jutted outcrop or incised road cut, we have the pleasure of directly viewing Earth’s skeletal structure.
Geologists map what lies beneath in order to visualize the processes that have formed rocks like desert sandstones or oceanic basalts over epochs and eons. A week ago they unveiled the mother of all maps. OneGeology, which culls scattered data from 79 participating countries, is like the GoogleEarth of rocks—its soul bare, the highways, forests, dirt, rivers and oceans completely stripped away. It is the first digital geologic map of the world and includes rock formations up to 3 billion years old, created during a time when only bacteria ruled the surface.
The map’s swirling colors may look more like art disguised as science, but they code layers of information about the type and age of the rocks beneath the ocean and land. Though invisible to us on a daily basis, the geography of geology affects our lives more than we might initially think. The distribution of all vital resources, from fossil fuels to valuable minerals like iron and copper, can be read in the rocks. So too can forecasts of earthquakes and volcanic eruptions. Today, engineers are busy looking at ways to bury toxic nuclear waste and sequester carbon dioxide out of the atmosphere—it’s up to geologists to study the burial sites that will hold these messes for as long as necessary (due to the ever-shifting nature of the continental plates, forever isn't an option).
Without even looking for a color key, it's easy from the map to understand one basic facet of our planetary geology. The zig-zagged but uniform lines of color that cover the world's ocean basins illustrate the even creation of new oceanic crust in the gurgling mid-ocean ridges and its spreading-out from these centers. The continents, by contrast, are created by more random, less predictable processes, their configuration constantly reshaped like a jigsaw puzzle in motion. This all takes place on time scales too long for us to possibly conceive, but still--what a fascinating way of understanding our planet.