Most geological processes unfold at less than a snail's pace. The tectonic plates that cover Earth's surface slog along, crashing into and sliding over one another at rates of only a few millimeters per year. Over millions of years, however, these unhurried liaisons raise mountain ranges. Wind, rain, and natural chemical erosion gradually rework the mountains into silt, clay, and dissolved minerals. Slowly, this inorganic detritus wends its way to the sea, where it joins a languid rain of dead marine organisms to form thick layers of ocean-floor ooze.
Note: To comment, Science News subscribing members must now establish a separate login relationship with Disqus. Click the Disqus icon below, enter your e-mail and click “forgot password” to reset your password. You may also log into Disqus using Facebook, Twitter or Google.