Exploring the Ocean • Since ancient times people have studied the ocean such as waters and ocean floor • It provides food and services, and serves as a route for trade and travel
The World’s Oceans • 71% of the Earth’s surface is covered by ocean water. • The oceans contain 97% of the earth’s water. • All the oceans and seas are actually one continuous body of water.
Oceans • The oceans are the Atlantic, Pacific, Indian. Arctic and Southern. • The Pacific Ocean is the largest ocean. • The area and volume of the Pacific Ocean are greater than the Atlantic and Indian combined.
Seas • A sea is a part of an ocean that is nearly surrounded by water. • The Mediterranean, Arctic and Black Sea are really part of the Atlantic Ocean.
Ocean Floor Makeup • The ocean floor has higher mountains, deeper canyons, and larger flatter plains. Earthquakes occur more often. • The rocks are very different. • The crust is thinner
Edges of the Continents • The shoreline is a boundary between where the land and the ocean meet. • The topography of the ocean floor is different from the topography of the continents
Continental Margin • The area where the underwater edge of a continent meets the ocean floor is called a continental margin. • A continental margin consists of a continental shelf, a continental slope and a continental rise.
Continental shelf • The flat part of a continental margin that is covered by shallow area of the ocean floor that extends outward from the edge of a continents is called a continental shelf.
Continental shelf • Depth of 130 meters and gets steeper • A continental shelf slopes gently from the shoreline. • The width of the continental shelf varies. • Large mineral, oil and natural gas deposits are found here.
Continental Slope • The steep edge of the continental shelf • At the edge of the continental shelf, the ocean floor plunges steeply 4 to 5 kilometers. • A continental slope marks the boundary between the crust of the continent and the crust of the ocean floor
Continental Rise • Separating a continental slope from the ocean floor is a continental rise. • A continental rise is made of large amount of sediments, rocks, plants and animals. • Sometimes the sediments are carried down the slope in masses of flowing water called turbidity currents, like an underwater avalanche.
Abyssal Plains • Large, flat areas on the ocean floor are called abyssal plains. • The abyssal plains are larger in the Atlantic and Indian than in the Pacific due to the deposition of sediments by large rivers. • The Pacific Ocean has large cracks that trap sediments and result in smaller abyssal plains.
Abyssal Plains • Abyssal plains close to the continent are made of mud, sand and silt. • Farther out on the abyssal plains, some of them contain the remains of tiny organisms that form ooze. • Where ocean life is not abundant, the floor of the ocean is covered with red clay
Plates • Pieces of earths crust along with parts of the upper mantle are called plates. • The plates move at an average speed of several centimeters per year-barely faster than your fingernails grow • This is what shaped the dramatic features of the ocean, such as mountains and trenches
Seafloor Spreading • Mid ocean ridge is along boundaries of plates that are moving apart orDivergingadding a new strip of rock to the ocean floor • Magma squeezes up through cracks • Magma hardens • Seafloor spreading is what produced our ocean floor • When plates come together or Converge, one plate sinks under the other
Mid ocean Ridges • The mid ocean ridges form an almost continuous mountain belt that extends from the Arctic Ocean down through the middle of the Atlantic Ocean around Africa into the Indian Ocean and across the Pacific Ocean , much as the line of stitches winds around a baseball. • In the Atlantic it is called the mid-Atlantic Ridge and in the Pacific, the Pacific-Antarctica Ridge.
Formation of Mid ocean Ridges • Mountain ranges on land are formed when the Earth’s crust folds and is squeezed together. • Mid ocean ridges are areas where molten material from deep within the Earth flows up to the surface and cools and forms new crust. • Has 2 parallel chains of mountains separated by valley and trenches
Submarine Canyons • In many areas, submarine canyons cut through a continental shelf and slope. • They are deep, V-shaped valleys that have been cut in the rock, possibly by turbidity currents. • The Monterey Submarine Canyon(2000 meters) is deeper than the Grand Canyon.
Rifts • Running along the middle of the mid ocean ridges between the rows of parallel mountains are deep crevices or rifts. • Rifts are areas of great earthquake and volcanic activity.
Trenches • Trenches are the deepest parts of the ocean found along the edge of the ocean floor. • Is a steep sided canyon in the ocean floor • The Mariana Trench in the Pacific Ocean contains the deepest spot on Earth- the Challenger Deep.
Mariana Trench • The Mariana Trench is 2, 542 km (1,580 miles) long (more than five times the length of the Grand Canyon) and 69 km (43 miles) wide • The Challenger Deep is 11,033 meters (36,201 feet), almost 7 miles • If Mount Everest, which is the tallest point on Earth at 8,850 meters (29,035 feet), were set in the Mariana Trench, there would still be 2,183 meters (7,166 feet or about 2 miles) of water left above it. • http://deepseachallenge.com/the-expedition/mariana-trench/ • https://www.youtube.com/watch?v=9FYKLS7xjpg
Properties of Ocean Water • Ocean water is a mixture of gases and solids dissolved in pure water. • Oceanographers believe oceans contain all the natural elements on Earth. • 85 of 90 elements have been found in the ocean.
Major Elements in the Ocean • Ocean water is 96% pure water. • Chlorine (1.9) and sodium (1.1) make up the next largest concentration of elements. • Sodium chloride is table salt.
Salinity • Salinity describes the amount of dissolved salt in the ocean. • Salinity is expressed in parts per thousand. • The average salinity of the ocean is 35 parts per thousand.
Sources of Salt in the Ocean • When volcanoes erupt, rock materials and gases, such as chlorine, spew forth. • As rivers, streams and glaciers move over rock and soil, they dissolve salts in them, such as magnesium, sodium and potassium. • As waves pound the shoreline, they dissolve salts from the rocks.
Gases in Ocean Water • The most abundant gases in ocean water are nitrogen, carbon dioxide and oxygen. • The amounts of these elements vary with depth. They are more abundant at the ocean’s surface where sunlight causes more plant life.
Temperature of Ocean Water • Warm water holds less dissolved gas than cold water. • When ocean water is cold, like in polar regions, it sinks and carries oxygen rich water to the ocean depths. • As a result, fish and other animals can live in deep parts of the ocean.
Temperature of Ocean Water • Sun is the major source of heat for the ocean. • Motions of the ocean, such as waves and currents, mix the surface water and transfer the heat downward.
Surface Zone • The zone where the water is mixed by waves and currents is called the surface zone. • The surface zone extends 100-400 meters downward. • The temperature remains constant with depth. • Temperature in a surface zone changes due to seasons and locations.
Thermocline • The zone of rapid temperature change is called the thermocline. • The thermocline does not occur at a certain depth. • The season and flow of ocean currents alter the depth of the thermocline. • The thermocline exists because warm, surface water does not mix easily with colder, denser water.
Deep Zone • The thermocline forms a transition between the surface zone and the deep zone. • The deep zone is an area of extremely cold water that extends from the bottom of the thermocline to depths of 4000 meters or more. • Within the deep zone, temperatures decrease only slightly. • At depths greater than 1500 meters, the temperature is about 4 degrees C. • The three ocean zones are not found in the polar (Arctic and Antarctica) regions since the surface waters are always cold.
Seamounts and Guyots • Seamounts are underwater volcanic mountains that rise more than 100 meters above the ocean floor. Most have been found in the Pacific Ocean. • Some seamounts reach above the surface of the water to form islands, like the Azores in the Atlantic and the Hawaiian islands in the Pacific. • Guyots are flat-topped seamounts.
Ocean Life Zones • Intertidal Zone (Splash Zone) • Neritic Zone (Continental Shelf) Open Sea Zones • Bathyal Zone (Continental Slope) • Abyssal Zone (Ocean floor)
Ocean Life Zones • The plant and animal life in the ocean is affected by several factors. • the amount of sunlight that penetrates the ocean. • the temperature of the ocean water. • Water pressure • The classification of the ocean into life zones is based on the conditions in the ocean. These conditions vary widely. • The classification includes the intertidal zone, the neritic zone and open-ocean zones.
Major Groups of Ocean Life • Plants and animals in the ocean are classified into three major groups based on their habits and the depth of the water in which they live. • Plankton • Nekton • Benthos
Plankton • Plankton float at or near the surface where sunlight can penetrate. • Most of the plankton are very small, such as algae. • These organisms drift with the currents or tides. • Plankton are the main food for many larger organisms. They account for most of the organisms in the ocean.
Nekton • Whales , seals , dolphins, squid, octopus, barracuda and other fish are all nekton. • Nekton are free-swimming organisms that feed on other nekton as well as plankton. • Many have adaptations enabling them to function at depths that have great pressure and no light.
Benthos • Organisms that live on the ocean floor are benthos. • The forms of these animals include crustaceans and shell fish. • The deep bottom environments are sparsely populated with benthos. • Some benthos are plants that live on the ocean floor in shallow waters where sun can penetrate.
Intertidal (Splash) Zone • This region is the most changeable in the ocean. • Anemones, crabs, clams, mussels and plants such as seaweed live here. • They must be able to exist without water for periods of time. • They must be able to anchor to keep from being washed out to sea.
Estuary • An environment along the oceans edge • Is a coastal inlet or bay where fresh water from a river mixes with salty ocean water. • Water is known as brackish.
Coastal Wetlands • Are habitats found in and around estuaries • Along the US coasts, most wetlands are either mangrove forests or salt marshes.
Salt Marshes • Have muddy soil that is rich in nutrients and dominant plant is cord grass • Tide channels running through the grass break up waves, thus protecting organisms from the ocean surf
Mangroves • Have arching prop roots that anchor the trees to the land • Roots break up wind and waves protecting organisms that live there • Roots also trap sediment so water is rich in nutrients
Neritic ( Shelf) Zone • This zone extends to a depth of 200 meters and receives plenty of sunlight. • The water pressure is low and the temperature is constant. • This zone can support plankton, nekton and benthos. • Marine life is most abundant here.
Coral Reefs • Can form only in shallow tropical ocean waters • Produce a hard material around their soft bodies • When they die, the hard material is left behind