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Unit C – Water Systems on Earth

Chapter 8 – Water Features

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8.1 – GEOLOGICAL FEATURES AT SEA AND ON LAND

Chapter 8 – Water Features

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Geological Features at Sea and Land

Alfred Wegener came up with the theory of continental drift which led to the development of the theory of plate tectonics

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Plate Tectonics Earth’s crust is

divided into huge sections called tectonic plates

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Plate TectonicsThe plates collide with, slide by,

slip under, and separate from each other forming a variety of features, both underwater and on land

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Continental Shelves Continental Shelf –

the gently sloping slope of the ocean floor as it extends outward from the continents

The continental shelf is a continental plate even though it is underwater

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Continental Slope Continental Slope –

the more steeply sloped region at the edge of the continental shelf

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Continental Rise Continental

Rise – a region of gently increasing slope where the ocean floor meets the continental slope

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The Ocean Floor The ocean floor is

beyond the continental slope and rise

Much of the ocean floor consists of large flat areas known as ABYSSAL PLAINS

Over time sediments from rivers and streams settle on the ocean floor filling up holes

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Underwater Mountains The longest mountain

range in the world is underwater – The Mid-Ocean Ridge

The mid-ocean ridge is home to many volcanoes

Volcanoes that formed underwater are called SEAMOUNTS

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Underwater Mountains Overtime the lava

builds up and forms a volcanic island – ex. Hawaiian Islands

Guyot – was once a volcanic island but has weathered and eroded enough that the ocean has covered it over again

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Canyons CANYONS – deep,

steep-sided valley. Most are formed by

rivers that cut their way through the surrounding rock. As the rivers run into the ocean they may continue to carve away the continental shelf

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Trenches TRENCHES – formed

when two oceanic plates collided

Trenches run parallel to the coast

Trenches may be 200 km wide and 2400 km long

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Lakes and RiversSee page 222 in text book

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Watersheds WATERSHED – an

area surrounded by high-elevation land, in which all water runs to a common destination

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The Continental Divide The CONTINENTAL

DIVIDE (or the Great Divide) – the crest of the Rocky Mountains that separates water flowing to the west from water flowing to the north and east.

See fig. 9 p.224 in txt

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8.2 – GLACIERS: RIVERS OF ICE

Chapter 8 – Water Features

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Glaciers Glacier- a mass of

ice and snow built up over thousands of years

Glaciers occur in high altitudes and near Earth’s poles

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Glaciers The lower layers

of a glacier are turned into clear ice by the weight of the snow above

This great weight also causes glaciers to ooze down mountains

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Glacial Features Over thousands of

years, the erosion by glaciers changes the shape of mountains and creates many geological features

These features are evidence of past glaciation

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Glaciers As the glacier

moves over uneven ground, the ice sheet breaks and produces deep cracks called crevaces

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Glacial Features Cirque – the

small beginning of a glacier, where snow, ice and the freeze-thaw cycle create armchair-like hollows in the sides of mountains

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Glacial Features Arête – a

landform created when two cirques on a mountain erode to each other and create a sharp ridge between them

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Glacial Features Horn- the sharp

pyramid shape formed on a mountain when three or more arêtes carve the mountain peak

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Glacial Features Hanging Valley-

where a small glacier meets a large glacier, and the valley floor of the large glacier is below the bottom of the small glacier

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Glacial Features Fiords- a long,

deep valley carved by a glacier that has become flooded by sea water

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Glacial Features Moraines- a large

ridge of gravel, sand and boulders that was pushed aside by a glacier or dragged to the end of a glacier

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Glacial Features Esker- a long

mound of sand and gravel marking the path of meltwater streams that passed through and under a glacier

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Glacial Features Striations- a

groove or scratch on the surface of rock; caused when boulders and gravel at the bottom of a glacier are dragged along the rock’s surface

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Glacial Features Erratic- a large

boulder that was carried by glaciers and then left behind on the land when the glacier receded

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Glacial Features Iceberg- a large

chunk of ice that breaks off of a glacier when the glacier reaches the ocean

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8.4 - Currents

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Currents Current- Movement of

water in an ocean or lake caused by temperature differences

A current caused by temperature differences is called a convection current

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Convection CurrentsHelp redistribute nutrients and

oxygen in lakes that are ice-covered in the winter.

Plants get nutrients from decaying plant matter and the upper layers of the water get oxygen from the plants below

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Ocean Currents

Convection currents exists in the worlds oceans on a global scale

See p. 232

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Gyres

Ocean Currents form consistent, circular patterns called gyres

GYRES- a large, consistent, circular pattern of ocean currents

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GyresThe five major gyres of the World

North Atlantic GyreSouth Atlantic GyreSouth Indian GyreNorth Pacific GyreSouth Pacific Gyre

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Gyres Each gyre is

made up of several currents

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Great Pacific Garbage Patch

http://www.youtube.com/watch?v=-K-lGDRZOqc&feature=related

http://www.youtube.com/watch?v=tnUjTHB1lvM

Rd p.235 in txt book

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8.5 – Water, Weather & Climate

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Water, Weather & ClimateSpecific Heat Capacity – is a measure

of a substance’s capacity to keep its heat Substances with a low specific heat capacity

require little heat before their temperature starts to rise

Substances with a high specific heat capacity require more heat energy to increase their temperature – these materials also take much longer to cool down because they have more heat energy to give off

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Water, Weather & ClimateWater has a high specific heat

capacity

Large bodies of water, such as oceans, warm up and cool down much more slowly than the surrounding land and can affect the weather and climate of an area

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Water, Weather & ClimateWeather Weather- the daily

atmospheric conditions, such as temperature, precipitation, and humidity

Climate Climate- the average

weather conditions over many years

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Water, Weather & Climate Water releases its

heat much more slowly than land. During the night, therefore, the land cools down more than the ocean.

The air over the land also becomes cool and pushes air out to the ocean. This is known as a land breeze.

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Water, Weather & Climate During the day,

the land warms up more than the ocean. The air above rises and a sea breeze blows in from the ocean

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Currents and ClimateOcean Currents have a major

effect on world climates

Rd Currents & Climate p.238 - 239

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8.6 - Waves

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Tsunami Tsunami – a large

wave caused by earthquakes, volcanic eruptions, or giant underwater landslides

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TsunamiTsunamis are barely noticeable

when they first form in the ocean <50cm high

Can travel at speeds of 800 km/h – when this energy is squeezed into shallow waters, it becomes concentrated, and the wave speeds up and increases in height

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Waves & WindWaves on lakes and oceans may

begin as wind pushes down unevenly on their surfaces.

As wind continues to blow across the surface of the water, the waves swell larger

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Waves and Wind Crest – top of the

wave

Trough- Bottom of the wave

Wavelength- distance between crests

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WavesWhen waves make their way across

water, it is energy that is moving, not water.

If you were floating in the water, you would not be swept across the surface at the same speed as the waves

You would be moved up and down in a circular pattern (see fig2 p.241)

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Wave PowerRead pages 242-243 in text book

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8.7 - Tides

The Moon & Tides

Tides- daily rise and fall in sea level caused by the gravitational pull of the Sun and Moon and the rotation of the Earth

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Tides Tidal Range- the

difference between water levels at high tide and low tide

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Causes of TidesThe Primary cause of ocean tides is

the gravitational pull of the Moon on Earth.

The water bulges out toward the Moon

On the opposite side of the Earth, there is also a bulge of water caused by the rotation of the Earth

As a result tidal bulges form

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Tidal Bulges Tidal Bulge – the rise

of the water level in an ocean in response to the gravitational pull of the Sun and the Moon and the rotation of the Earth

Spring Tides Spring Tides

are strong tides with a high High Tide and a low Low Tide because the Moon and Sun are in a straight line and both their gravitational pulls are influencing the tides

When do spring tides occur?

Tides

Neap Tides Neap tides are weak tides with the least distance between High tide and low tide because the Gravitational pull of the Moon and the Sun cancel each other’s effect.

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TidesRead p. 244-247