Earth's Landforms: Shapes, Spheres, and Features
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Presentation Transcript
Chapter 6 Landforms
Measuring Earth • The Earth is not a perfect circle it is an oblate spheroid. • The earth is actually very close to the shape of a ping pong ball. • The equatorial diameter of Earth is 12,756km. • Its polar diameter is 12,714km • Proof: Pics from space, the fact that ships sink over the horizon, changes in gravity.
Spheres of Earth • The layer of gases that are above the water and rocky materials of the earth are called the atmosphere. • The Lithosphere is the hard rocky outer crust of the earth’s surface. • The hydrosphere is the sum of all the water that covers the surface of Earth
Plains • Plains are large, flat, often found in the interior regions of continents. • They are ideal for agriculture, and usually have thick, fertile soil, and large grassy meadows, that are ideal for grazing animals. • When a plain is close to the ocean, it is called a coastal plain. • Interior plains and coastal plains make up half of all the land in the U.S.
Plains • A coastal plain is also known as a lowland, because it is lower in elevation, than the land around it. • We find interior plains between the Rocky Mountains and the Appalachian Mountains. • The largest of all the plains, the Great Plains, lies between the Rockies and the Mississippi River.
Plateaus • Plateaus are flat, raised areas of land made up of nearly horizontal rocks that have been uplifted by forces within the Earth. • They differ from plains because their edges rise steeply from the land around them. • Because of their hight due to the uplifting, it is common for plateaus to be cut through by deep river valleys and canyons. • Ex: The Colorado River cut deep into the rock layers of a plateau to form the Grand Canyon.
Mountains • Mt. Everest is the tallest mountain at 8,800 meters above sea level. • There are 4 types of mountains: • Folded mountains • Fault-block mountains • Upwarped mountains • Volcanic mountains
Folded mountains • Folded mountains have layers of rock that appear to be folded like a rug. • Ex: Appalachian and Rocky mountains of Canada.
Upwarped Mountains • Upwarped mountains form when blocks of Earths crust are pushed up by forces inside of the Earth. • They have high peaks and sharp ridges. • Ex: Adirondack and Black Hills mountains
Fault-block Mountains • Fault-block mountains are made of huge, tilted blocks of rock that are separated from surrounding rocks by faults, or large fractures in rock. • These mountains have majestic peaks and steep slopes. • Ex: The Grand Teton and Sierra Nevada mountains of Wyoming and California.
Volcanic Mountains • Volcanic mountains form when molten material reaches the surface through a weak area of the crust. The deposited materials pile up, one on top of another until a cone-shaped structure forms. • Ex: Mt. St. Helens in Washington
Latitude & Longitude • Latitude and longitude lines on the globe form an imaginary grid system that allows people to locate any place on Earth. • Latitude lines, or parallels, are lines that run parallel to the Earth’s equator, which is a line that circles the Earth, half way between the North and South poles. • The Equator separates the Earth into Northern and Southern Hemispheres. • Latitude lines never cross and are measured in degrees. Oo is the equator and each pole North and South is 900. Go in 15 degree intervals. • Below the equator is called South latitude and above the equator is North latitude.
Latitude & Longitude • Longitude lines or meridians, are vertical lines on either side of the prime meridian. • The prime meridian acts as a reference point for longitude lines, just like the equator was a reference line for latitude. • The prime meridian is O0 the longitude lines go up in intervals of 150 around the globe to 180o. • Areas east of the prime meridian are east longitudes and west of the meridian they are west longitudes.
Prime Meridian • The meridian does not circle the globe like the equator. It runs from the North pole, through Greenwich, England to the South pole. • The meridian opposite the prime meridian is the 180 meridian. • When giving latitude and longitude coordinates we always give the latitude position first.
Time Zones • Time is measured by tracking Earth’s movement in relation to the Sun. • Each day is 24 hrs long, so we divide the Earth into 24 different time zones. • Each time zone is 15o of longitude wide and is 1 hr different than the zones on either side of it. • The U.S. has 6 time zones.
International Date line • You lose and gain time as you enter different time zones. If you travel far enough you will lose or gain a whole day. • The international date line is a transition line for calendar days and is near longitude line 180. • If you travel West across the date line you move your calendar forward a day. • If you travel east and cross the date line you move your calendar back a day.
Maps • Maps are made as projections. A projection is made when points and lines on a globe are transferred to paper. • Projections are made different ways and usually distort the shapes of the land masses on them.
Mercator Projection • Used a lot on ships, but distorts the land masses a lot.
Robinson projection • Here the continent shapes are more accurately depicted. And the longitude lines are curved like on a globe.
Conic Projection • These are used to to produce maps of small areas, and are not good for mapping the poles. They are made by projecting points and lines of a globe onto a cone.
Topographic Maps • These maps model the changes in elevation on Earth’s surface. They help to identify hills, mountains, and valleys. • These maps have contour lines that connect points of equal elevation. • If the change in elevation is steep the contour lines are close together. If it is not steep but slight then the lines are farther apart. • The difference in elevation b/w two contour lines is called a contour interval.
Map scales and Legends • A map scale shows you how to calculate a distance on a map in comparison to actual distance on the Earth. Ex: 1 inch=10miles. • A map legend is used to explain what symbols on a map mean.
Geologic Maps • These maps are used to show the arrangements and types of rocks that are at the Earth’s surface. • These maps are used to locate and extract natural resources.
3-dimentional maps • Sometimes 2-D maps like topographic and geological maps are not the best ways to depict an area. • So we use 3-D computerized maps to get a better idea of the surface features of land.
