Chapter 16) Lesson 1: Oceans Flashcards
the pacific ocean
the largest and deepest ocean. Larger than all of Earth’s combined land area.
the atlantic ocean
2nd largest ocean. Half the size of the Pacific. It occupies about 20 percent of Earth’s surface.
Indian Ocean
3rd largest Ocean Found between Africa, India, and the Indonesian islands.
southern ocean
Surrounds Antarctica. 4th largest Ocean. Some of its surface covered with ice year round.
arctic ocean
found near the North Pole. Smallest and shallowest ocean. Ice covers some of its surface year round.
when did earth’s oceans begin to form?
Earth’s oceans began to form as early as 4.2 billion years ago. It happened just a few hundred million years after the Earth formed.
How did earths oceans form
Early volcanos erupted huge amounts of
Water vapor in the atmosphere
condensed to form cloud droplets and rain. This rain fell for tens of thousands of years, collecting in Earth’s low-lying basins
and forming the oceans.
what is the other possible cause of the oceans forming
Evidence shows that a second source of water came from many icy comets and asteroids from space colliding with Earth.
how did plate tectonics affect the oceans formation
the shape and size of the oceans change due to plate tectonics. However, the volume of water in the oceans has remained fairly constant since the first oceans formed.
what makes ocean water salty
Rain water washes over rocks and dissolves minerals. (salts) These minerals are brought to the oceans by streams and rivers. Some minerals are released into the ocean by underwater volcanoes. Together these make the ocean water salty.
what is salinity
a measurement of the mass of dissolved solids in a mass of water. Expressed in parts per thousand (ppt) or parts per hundred (%)
sea water
is water from the sea or ocean that has an average salinity of 35 ppt.
brackish water
saltwater and freshwater mixed together.
salinity of brackish water
1 ppt to 17 ppt.
continental margins
Made of of 3 regions.
continental slope
extends from the continental shelf to the deep ocean.
continental shelf
the shallowest part of the continent plate near the shore.
continental rise
found at the base of the slope where sediments accumulatethat fall from the continental slope.
Abyssal Plain
large, flat areas of the seafloor that extend across the deepest parts of the ocean floor.
what forms the abyssal plain
thick layers of sediment
Underwater volcanoes can rise out of
the abyssal plains and form what
islands
mid-ocean ridge
form a continuous mountain range that extends through all of the Earth’s ocean basin.
what is the longest mountain range on earth
mid-ocean ridge
where is new ocean floor formed
the mid-ocean ridge
