PHYSICAL FEATURES OF EARTH

GENRAL SCIENCE

Presented To

Ms. AFSHEEN KHALIL

Presented By

HASSAIN ZAIB KHAN – BBA(Hons) MAJU

AGENDA• GLACIERS• MOUNTAINS• HILL• VALLEY• PLATEAUS• PLAINS• EARTHQUAKES• VOLCANOES• LAKES• RIVERS• DESERTS

GLACIER• A glacier is a huge mass of ice that flows slowly over

land. They form in the cold polar regions and in high mountains.

• Glacier ice is the largest reservoir of fresh water on Earth,

• Glaciers are formed when more snow falls during the winter than melts and evaporates in summer.

• Worlds largest glacier

• It's called the 'lambert Glacier' in Antarctica

MOUNTAINS

• Mountain is a landform that extends above the surrounding terrain in a limited area. A mountain is generally steeper than a hill.

• Mountains are created over long periods of time by tremendous

forces in the earth. Mountains are formed by volcanism, erosion, and disturbances or an uplift in the earth's crust.

• The earth's crust is made up of 6 huge slabs called plates, which fit together.

• When two slabs of the earth's crust smash into each other the land can be pushed upwards, forming mountains.

• Mountains cover 54% of asia, 36% of north america, 25% of europe, 22% of south america, 17% of australia, and 3% of africa.

The Tallest Mountain In The World When

Measured From Base To Summit

• Mauna Kea is the tallest mountain in the world when measured from base to summit

• The base of Mauna Kea is 19,678 feet below sea level and its summit is 13,796 feet above sea level.

• That gives Mauna Kea a total height of 33,474 feet from its base to its summit.

• It is actually a taller mountain than Mt. Everest which is 29,035 feet tall and is entirely above sea level from base to summit.

Asia Has The Lowest And Highest Points On Earth

• The lowest and highest points on the Earth surface are found in Asia.

• These are the shore of the Dead Sea which is 418 meters (1,371 feet below sea level) and Mount Everest which is 8,850 meters (29,035 feet above sea level). Mount Everest is rising at a rate of around 2.5 centimeters per year.

HILLS

• A natural elevation of the earths surface, smaller than a mountain.

• Hills may be formed by a buildup of rock debris or sand deposited by glaciers and wind.

• Hills may be created by faults.

• Faults are a slight crack in the earth which can cause earthquakes. Hills are formed when these faults go slightly upward.

VALLEYS

• Valleys are the low areas between or near mountain ranges.

• V-shaped valleys are formed by the erosive effects of running water and U-shaped valleys are formed by the erosive effects of flowing glacial ice.

PLATEAUS

• A plateau is a large highland area of fairly level land separated from surrounding land by steep slopes. Some plateaus, like the plateau of Tibet, lie between mountain ranges. Others are higher than surrounding land.

• The largest and highest plateau in the world is the Chang Tang of Tibet, called the "roof of the world“.

• which is still being formed by the collisions of the Indo-Australian and Eurasian tectonic plates.

PLAINS

• Plains are broad, nearly level stretches of land that have no great changes in elevation. Plains are generally lower than the land around them; they may be found along a coast or inland.

• Somewhat more than one-third of the Earth's land area is occupied by plains.

• Plains are usually well populated because the soil and terrain are good for farming.

EARTHQUAKE• Earthquakes are vibrations caused by sudden

movements of the Earth’s crust.

• Earthquakes can happen anywhere: land, mountains and oceans.

• Most earthquakes happen when two rock plates meet, creating friction. The force is so strong it will send shockwaves through the ground, creating an earthquake.

• The vibrations of an earthquake, known as seismic waves.

• Earthquake vibrations are detected, measured, and recorded by an instrument called a seismograph.

VOLCANOES

• The name Vulcano originates from Vulcan, a god of fire in Roman mythology.

• A volcano is an opening in the ground that spits out hot gases, rock and lava. The eruption can be so bad it can blow the top off the mountain.

• A volcano is formed when plates hit each other. One of the plates goes under the other. This is where the earth heats and melts the rock into magma and gases. This can happen as deep as 100 miles below the earth. Magma settles in pools or chambers near the surface. This is where eruptions take place.

VOLCANOES

• Volcanoes can also be formed when the plates go away from each other. The magma pushes up and lava forms. These types of volcanoes are found on the ocean floor.

• There are more than 500 active volcanoes in the world.

• The world's largest active volcano is Mauna Loa in Hawaii. Taller than Mount Everest,

Things That Come Out Of A Volcano

• Lava - 2012º F--sticky--hardens when cooled • Rock fragments - sticky magma--pressure

breaks it into fragments • Volcanic dust - 1/400 inch in diameter--can be

carried around the globe -- bright red • Volcanic ash - fragments 1/5 inch in diameter • Volcanic bombs - size range from baseballs to

basketballs • Gas - mostly steam - with carbon dioxide,

nitrogen, sulfur dioxide

LAKES• Lakes are bodies of water surrounded by land. Lakes

generally have fresh water, while oceans and seas have salt water.

• Lakes were formed many thousands of years ago by glaciers. At that time, huge glaciers covered the earth. When the glaciers melted, some of the water that was over hollows in the earth became lakes.

• Many lakes are artificial and are constructed for hydro-electric power supply, recreational purposes, industrial use, agricultural use, or domestic water supply.

BIGGEST AND SMALLEST LAKE

• The world biggest lake

• The biggest lake in the world is "Caspian Sea" in Asia. It covers an area of 371 000 km2 (143 244 sq miles).

• Its called a sea because when the romans first visited the lake they found the water to be salty.

• The smallest lake

• Ontario (in North America)

RIVER• A river is fresh water flowing across the surface of the

land, usually to the sea. It flows in a channel. The bottom of the channel is called the bed and the sides of the channel are called the banks.

• When one stream meets another and they merge together, the smaller stream is known as a tributary. It takes many tributary streams to form a river.

• All rivers start at the highest point in an area. As the river flows downstream, it gains more water from other streams, rivers, springs, added rainfall, and other water sources.

• The longest river

• The Nile River in Africa is the longest river in the world. It's about 4150 miles long.

• Shortest River

• The D River (in Oregon) is the shortest one America has. It is merely 120 feet long. It connects Devil's Lake with the Pacific Ocean.

LONGEST AND SHORTEST RIVER

DESERTS

• A Desert is a landscape form or region that receives very little precipitation.

• A desert is an area that is very dry. It is the lack of moisture that truly defines a desert, not it's temperature or location.

How Do Deserts Form?

• All deserts form due to very little rain or snow over long periods of time.

Are Deserts Expanding?

• Already one third of the world is considered desert and many deserts are expanding.

• The Gobi desert in China has expanded every decade since the 1950s. In a 5 year period ('94-'99) the Gobi desert expanded over 20,000 square miles (1).

• The Sahara desert in Northern Africa has spread South over 250,000 square miles in the past 50 years. Sahara is the largest desert in the world at 3.5 million square miles.

• The growth of deserts is called desertification,

• Little research has been done on how global warming might affect deserts. The Environmental Protection Agency even points out that while one model shows an increase in deserts by 185%, another shows a decrease by 56% .With such uncertainty it is too difficult to determine how much if any of desertification is due to global warming.