National Geographic : 2012 Sep
-4,000 ft -2,000 ft -8,000 ft -6,000 ft -10,000 ft -12,000 ft -14,000 ft Tour of a Seamount Undersea mountains, mainly volcanic in origin, rise in the hundreds of thousands from the ocean oor. One of Earth's most prominent physical features, they compare in size with terrestrial mountains but are likely more numerous. The Chrysler Building, 1,046 feet high, is shown to scale against this depiction of Cross Seamount, which is over 14,000 feet tall. OCEAN CURRENTS Undersea mountains take many forms---from this flat-topped guyot to smaller pinnacles to vast rolling hills with bases spanning 50 miles or more. Surfaces may be sculpted with craters, crevices, and ridges. UPWARD FLOW Currents collide with the base and acceler- ate upward, carrying cold, nutrient-rich water toward areas near the surface and providing food for animals living in the vicinity.