Earth Science Spring 2013

The Water Planet Global ocean covers 97% of the earth’s surface. Global ocean divided into 3 major oceans: Atlantic Pacific Indian Sea- small areas of ocean that are partially surrounded by land Ex: Mediterranean, Caribbean, & Coral

The Water Planet Each ocean has special characteristics Arctic Ocean (northern part of the Atlantic)- water near the surface is less salty than water in the other oceans Pacific Ocean- largest feature on Earth’s surface Deepest ocean Sea of Japan, Bering, Coral, and South China seas are all parts of the Pacific Ocean Atlantic Ocean- 2 nd largest ocean Mediterranean, Caribbean, and Baltic seas & Gulf of Mexico are all parts of the Atlantic Ocean Indian Ocean- 3 rd largest ocean Arabian & Red Seas are part of the Indian Ocean

Exploration of the Ocean Oceanography- study of the physical characteristics, chemical composition, & life forms of the ocean : H.M.S Challenger laid the foundation for modern oceanography Today there are many ships equipped to perform oceanographic research Ex: JOIDES Resolution Ocean floor- made up of continental & oceanic crust that lie beneath the ocean waters

Exploration of the Ocean Submersibles Underwater research vehicles Some are piloted by people More advanced ones are robotic Photograph & collect samples from the ocean floor Several types have been used Bathysphere- spherical vessel that was first used for deep-ocean exploration (manned) Bathyscaph- self propelled, free-moving submarine equipped for deep-ocean research (manned) Robot submersibles- allow exploration of great depths & for long periods of time

Exploration of the Ocean Sonar Sound Navigation and Ranging Consists of a transmitter & a receiver Transmitter- sends out a continuous series of sound waves from the ship to the ocean floor Receiver- sound waves hit the ocean floor & reflect back up to the receiver Amount of time it takes the waves to go round trip determines the depth

Features of the Ocean Floor 2 major divisions of ocean floor Continental margins Shallower portions of the ocean floor Made up of continental crust & a thick sediment wedge Deep ocean basin Deeper portion of the ocean Made up of oceanic crust & a thin sediment layer

Features of the Ocean Floor: Continental Margins Continental Shelf Edge of a continent covered by shallow ocean water Usually slopes gently Average depth of water 60 meters Part of the continental margin Affected by changes in sea level

Features of the Ocean Floor: Continental Slope Continental Slope Steep incline at the edge of the continental shelf Boundary between continental & oceanic crust is at the base of the continental slope Ocean depth increases to thousands of meters Continental shelf & continental slope maybe cut by deep v- shaped valleys Submarine canyons Often associated with the mouths of major rivers Turbidity currents- dense current that carries large amounts of sediment down the continental slopes Continental rise- accumulation of sediments at the base of the continental slope

Features of the Ocean Floor: Deep Ocean Basins Trenches Deep valleys in the ocean floor Ex: Mariana Trench- deepest place in the world, estimated to be 11,000m deep Most are located along the Pacific Ring of Fire Associated with earthquakes, volcanic mountain ranges, volcanic island arcs

Features of the Ocean Floor: Deep Ocean Basins Abyssal Plains Extremely flat areas that lie deep beneath the ocean Cover about half of the deep-ocean basin Flattest regions on earth Made up of deposited sediments

Features of the Ocean Floor: Deep Ocean Basins Mid-Ocean Ridges Continuous series of underwater mountain ranges that run along the floors of all the oceans Form when plates pull away from each other Rift along the crest New crust is formed here Fracture zones – series of faults forms due to the different rates at which the mid-ocean ridge separates

Features of the Ocean Floor: Deep Ocean Basins Seamounts Submerged volcanic mountains at least 1000m tall Generally associated with hot spots Hawaii & Canary Islands are seamounts that have risen above the ocean surface Guyots (GEE-oze) – flat-topped, submerged seamount Cause by erosion and the sinking of ocean crust

Ocean-Floor Sediments Sediments closer to shore are generally coarser than those found in the deep-ocean basins Sediments come from 2 things: Washed into the ocean by rivers Wave erosion of the shoreline Core samples- cylindrical sample of sediments from the deep-ocean floor

Ocean-Floor Sediments: Sources Inorganic Sediments Rock particles carried by rivers Volcanic dust that has been blown far out to sea by the wind Icebergs carry large amounts of sediments which are deposited as they melt Cosmic dust from meteorites that have been vaporized in the atmosphere

Ocean-Floor Sediments: Sources Organic Sediments Remains of marine plants and animals 2 common substances in organic sediments Silica (SiO 2 ) Calcium Carbonate (CaCO 3 )

Ocean-Floor Sediments: Sources Chemical Deposits Materials that are formed during chemical reactions that take place in the ocean. Nodules of minerals form on abyssal plains Composed mainly of oxides of manganese, nickel, and iron

Ocean-Floor Sediments: Physical Classification 2 general types of sediments found on the ocean floor Muds- very fine silt and clay sized particles of rock that have settled to the ocean floor Ooze- soft organic sediment on the ocean floor At least 30% organic materials & rest is made up of fine mud 2 types of ooze Calcareous ooze- mostly calcium carbonate Siliceous ooze- mostly carbon dioxide