CHAPTER 13 NOTES: OCEAN WATER AND OCEAN FLOOR About 71% of the Earth’s surface is covered in water Four Oceans: Arctic Ocean (4%) Indian Ocean (20%) Atlantic Ocean (28%) Pacific (48%)

How do scientists think the oceans were formed? 2 Thoughts??????? 1st thought---- When the Earth first formed, there were many volcanoes all over the surface. Since there is a lot of water vapor contained in lava, it rose into the young atmosphere during eruptions. As this water vapor condensed, it formed clouds, which eventually led to the rains that lasted for many years.

2nd thought Comets and water-rich asteroids from the outer reaches of the asteroid belt and the Kuiper Belt collided with a pre-historic Earth bringing water to the world’s oceans. Video Clip on How the Earth got its Oceans

Video Clip on Earth’s Oceans https://www.youtube.com/watch?v=_LpgBvEPozk

The ocean has many different elements dissolved in it. OCEAN WATER The ocean has many different elements dissolved in it. These elements such as chloride and sodium---which are the two most abundant elements---started out in rocks. Water and acids eroded the rocks, and rivers carried the elements into the sea.

The average salinity of the ocean is 35‰ The average salinity of the ocean is 35‰. The oceans usually contain 35 parts of salt for every 1,000 parts of sea water. Salinity is lower in some places where there is a lot of fresh water coming into the ocean (near river deltas). Salinity is higher where the Sun is very strong and evaporation is greater than precipitation. You Decide…

Natural Processes Affecting Salinity Makes no sense without caption in book https://www.youtube.com/watch?v=EqpJZGyS4Bw

THREE TEMPERATURE ZONES 1. Surface (sea level down to 300m) 2. Thermocline (300m-700m)an area of rapid temperature decrease with increased depth 3. Deep water (700m-bottom) Surface Zone Deep Water

THE IMMENSE OCEAN FLOOR The partially submerged outer extension of a continent is called the continental margin which is made of continental crust. The continental margin is divided into different regions: 1. Shelf extends outward from the continent 2. Shelf break (where shelf ends and slope begins) 3. Slope 4. Rise (only in passive) 5. Abyssal plain aka the flat part of the ocean floor 6. Trench (only in active)

TWO TYPES OF MARGINS: PASSIVE---not near plate boundaries--- Passive continental margins are those passively moving away from sites of seafloor spreading PASSIVE CONTINENTAL MARGIN EXAMPLE: ATLANTIC OCEAN

EXAMPLE: PACIFIC OCEAN ACTIVE---near plate boundaries--- Active continental margins are those found in subduction zones, where trenches are created ACTIVE CONTINENTAL MARGIN EXAMPLE: PACIFIC OCEAN What feature do you see in the active continental margin that you did not see in the passive continental margin? trench

LIFE IN THE OCEAN There are 3 groups of ocean life: PLANKTON— microscopic floaters like phytoplankton 2. NEKTON— free swimmers like fish, whales and sharks BENTHOS— bottom feeders that live in the sand, like clams and crabs

PLANKTON (floaters) PHYTOPLANKTON ZOOPLANKTON

NEKTON (swimmers) Squid Whales Shark Fish

BENTHIC ORGANISMS (bottom dwellers) Starfish Cluster Shrimp Sea Cucumber Lobster Coral Hermit Crab

Questions 1.) Why is the ocean salty? 2.) What are the 4 oceans? 3.) How do scientists believe that the oceans formed? 4.) Is there anything that you did not understand and need clarification? Please write your responses on your own paper. Make sure your name is on it and turn it in!