Warm-up What is one topic from this unit that you understand? What is one topic that you are still confused about?

Oceanography Review Chapters 15 and 16

Oceans Oceanography- the study of Earth’s oceans Water could have originated one of two ways on Earth: Comets hitting Earth Volcanic eruptions emitting gasses

Oceans Sonar Satellites Today we can use SONAR and satellites to study the oceans. Satellites SONAR is used to measure ocean depth D = ½ (time x velocity) d = ½ (sec x 1500m/sec) Speed of sound in water Sonar

Oceans cover approximately 71% of the Earth’s surface Ocean Water Oceans cover approximately 71% of the Earth’s surface

Ocean Water Oceans cover about: 61% of the northern hemisphere 81% of the southern hemisphere Northern Hemisphere Southern Hemisphere

Chemical Properties of Seawater Ocean water is made up of several different elements that make it “salty”

Chemical Properties of Seawater Salinity is a measure of the amount of dissolved salts in seawater. Salinity is measured in grams of salt per kilograms of water, or parts per thousand (ppt)

Chemical Properties of Seawater The average salinity of seawater is 35 ppt or 3.5%

Chemical Properties of Seawater Salinity can be increased by: Weathering and erosion of rock Volcanic activity Evaporation Salinity can be decreased by: Precipitation Runoff Iceberg and sea ice melting

Ocean Layers The ocean can be divided into 3 layers based on temperature Surface layer Transitional thermocline Bottom layer Surface Layer Thermocline Bottom Layer

Thermocline - a zone of rapid temperature change Thermocline - a zone of rapid temperature change. As depth INCREASES temperature DECRESES

Water Density Water density is affected by temperature and salinity Cold water is more dense and sinks to the bottom Warm water is less dense and rises Salinity Higher salinity leads to increased density Higher density water sinks.

Currents Density Currents- caused by the differences in temperature and salinity in deep water Surface Currents- caused by winds.

Gulf Stream Northern Hemisphere, currents flowing toward the pole are warm Southern Hemisphere, currents flowing towards the pole are cold Cold+salt = dense water In the North Atlantic Ocean, the water becomes so dense - begins to sink down through less salty and less dense water: Density Current

Gyres - circular ocean currents caused by landmasses and the Earth’s rotation Coriolis effect – ocean currents in the northern hemisphere are deflected to the right and currents in the southern hemisphere are deflected to the left Upwelling - Vertical movement of ocean water

Tides Tides - the periodic rise and fall of ocean levels Normally there are 2 high tides and 2 low tides per day. This pattern is called a semidiurnal tide

Neap Tides Spring Tides Occur when the Sun, Moon and Earth form a right angle. High tides are lower, low tides higher than normal Spring Tides Occur when Sun, Moon and Earth are aligned High tides are higher and low tides lower than normal

Ocean Waves Wavelength- distance from one point to the same point on the next wave Crest- top of a wave Trough- bottom of a wave Wave- rhythmic movement that carries energy through matter or space

Shoreline Features A beach is the accumulation of sediment along the shore of a lake or ocean. Waves are constantly eroding, transporting, and depositing sediment resulting in many shoreline features.

Shoreline Features A barrier island is a long, narrow sandbar parallel to, but separated from, the mainland.

Shoreline Features An estuary is the area where a river or stream enters the ocean. Causes brackish water- a combination of fresh and salt water.

Changes in Sea Level Melting of glaciers and ice sheets causes global sea levels to rise. Rising sea levels can cause flooding in coastal areas.

The Seafloor The deepest place in the ocean is the Mariana Trench in the Pacific Ocean.

The Seafloor The continental margin is the submerged part of a continent.

The Seafloor The continental shelf is the shallowest part of a continental margin from the shore to the open ocean.

The Seafloor The continental slope is the area where the seafloor drops off towards the abyssal plain. It is the true edge of the continent. HERE!

The Seafloor The continental rise is sloping accumulation of deposits that form at the base of the continental slope. HERE!

The Seafloor The ocean basins make up 60% of the Earth’s surface. An abyssal plain is a smooth, flat, bottom part of the ocean. They are the flattest surfaces on earth.

The Seafloor A trench is a deep depression in the seafloor. The deepest parts of the oceans are found in trenches (This is where subduction occurs)

The Seafloor The mid-ocean ridge is a chain of underwater mountains that run through the ocean basins. A rift valley is the middle part of the mid ocean ridge.

A. Continent B. Submarine Canyon K. Continental Shelf I. Volcanic Island C. Continental Slope D. Seamounts H. Midocean ridge E. Guyot J. Rift Valley G. Trench F. Abyssal Plain