Seafloor Spreading - NOAA/PMEL

Our Earth is a warm planet sailing through cold space. Much of the rocky interior (the mantle) of our planet is hot enough to flow, like a candy bar kept too long in one’s pocket. The surface of the Earth, however, is chilled by the cold of space, and so the familiar rocks of the Earth’s surface are hard and brittle. The cold outer layer of our planet, which holds together as a rigid shell, is not made of one solid piece. Instead this shell is broken into many separate pieces, or tectonic plates, that slide around atop the mobile interior.

The tectonic plates are in motion. They are driven by the flowing mantle below and their motions are controlled by a complex puzzle of plate collisions around the globe. There are three types of plate-plate interactions based upon relative motion: convergent, where plates collide, divergent, where plates separate, and transform motion, where plates simply slide past each other. Seafloor Spreading is the usual process at work at divergent plate boundaries, leading to the creation of new ocean floor. As two tectonic plates slowly separate, molten material rises up from within the mantle to fill the opening. In this way the rugged volcanic landscape of a mid-ocean ridge is created along the plate boundary.

Other NeMO-related concepts: Mid-ocean ridges | seafloor spreading | seamounts & hot spots | calderas | Axial volcano Hydrothermal vents | fluid paths | focused vents | diffuse vents | sulfide | anhydrite Animal Gallery | chemosynthesis | biological colonization of new lava Lava morphology | sheets | pillows | lava contacts | skylights | pillars | the 1998 flow NeMO at Axial | the 1998 eruption | the rumbleometer story | lava flow animation