Page 41 - (DK) Ocean - The Definitive Visual Guide

OCEANS ARE ALMOST as old as

Earth itself. Sediments were probably

accumulating underwater about 4 billion
years ago, around the time that the oldest

known rocks on Earth were forming. And

yet the ocean floor is very young. Discovery

of the processes that create and rapidly

recycle the ocean floor led to our modern
understanding of plate tectonics. These

processes give Earth a surface quite

unlike those of our planetary neighbors,
with deep ocean basins and high-standing

continents. The positions of the oceans

and continents are not fixed, but driven

by heat flow deep within the planet. An

understanding of ocean geology opens
a window on Earth’s interior, as well as

providing insights into the global climate

and the evolution of life on Earth.

OCEAN GEOLOGY

OCEANIC LAVA
Steam mixes with surf as lava from Kilauea
Crater reaches the Pacific Ocean on the south
shore of Hawaii. Basaltic lava such as this
makes up the oceanic part of Earth’s crust.