Creation and Collection of Water
When the Earth was formed 4.6 billion years ago, it would never have been called the Blue
Planet. There were no oceans, there was no oxygen in the atmosphere, and no life. But
there were violent collisions, explosions, and eruptions. In fact, the Earth in its earliest stage
was molten. This allowed elements to separate into layers within the Earth — gravity pulled
denser elements toward the Earth’s center, while less dense materials accumulated near the
surface. This process of separation created the layers of the Earth as we know them.
Astemperaturescooled, thesurfacesolidifiedandanatmospherewascreated. Volcanicerup-
tions released water vapor from the Earth’s crust, while more water came from asteroids and
comets that collided with the Earth (Figure14.1). About 4 billion years ago, temperatures
cooled enough for oceans to begin forming.
Figure 14.1: Volcanic activity was common in Earth’s early stages, when the oceans had not
yet begun to form. ( 11 )
Present Ocean Formation
As you know, the continents were not always in the same shape or position as they are
today. Because of tectonic plate movements, land masses have moved about the Earth since
they were created. About 250 million years ago, all of the continents were arranged in one
huge mass of land called Pangea (Figure14.2). This meant that most of Earth’s water
was collected in a huge ocean called Panthalassa. By about 180 million years ago, Pangea
had begun to break apart because of continental drift. This then separated the Panthalassa
Ocean into separate but connected oceans that are the ocean basins we see today on Earth.