8 TH GRADE SCIENCE

1. 8TH GRADE SCIENCE COMPARE AND CONTRAST THE DIFFERENT LANDFORMS CAUSED BY EARTH’S EXTERNAL FORCES. ESS 8.8.4

2. PLAINS • Plains are large, relatively flat areas of land. • Plains found near the ocean are called coastal plains. • Flat, grassy areas used to grow crops or for grazing are also plains. • Together, these 2 types of plains make up one-half of all of the land in the united states.

4. COASTAL PLAINS • Coastal plains are broad areas along the ocean’s shore. • They are often called lowlands because of their low elevations. • The Atlantic Coastal Plain stretches along the east coast of the United States. • This area is characterized by low rolling hills, swamps, and marshes.

5. Coastal Plains • The Atlantic Coastal Plain isn’t perfectly flat. • It has many low hills and valleys that have been carved by rivers. • The Atlantic Coastal Plain formed under water about 70 million years ago from sediments composed of marine organisms that fell to the ancient ocean floor. • When the sea level dropped, the plain was exposed.

6. Coastal Plains

8. GULF COASTAL PLAIN • Another example is the Gulf Coastal plain. • It includes the lowlands of the southern United States that surround the Gulf of Mexico. • Much of this plain was formed from sediments deposited by the Mississippi River as it entered the Gulf of Mexico.

9. Texas Gulf Coast

12. Mississippi / Louisiana Gulf Plains

14. Interior Plains • A large portion of the interior Plains is referred to as the Great Plains. • They lie between the Mississippi lowlands and the Rocky Mountains. • The Great Plains are flat, grassy, dry plains with few trees.

15. Interior Plains • A large portion of the center of the United States is called the Interior Plains. • They extend from the Appalachian Mountains in the east to the Rocky Mountains in the west, to the Gulf Coastal Plain in the south. • They include the rolling hills of the Great Lakes area and the central lowlands around the Missouri and Mississippi rivers.

17. Great Plains • They are also called High Plains because of their elevation. • They range from 350 meters above sea level at their eastern border to 1500 meters at their western boundary. • The Great Plains are covered with nearly horizontal layers of loose materials eroded from the Rocky Mountains. • Streams deposited these sediments over the course of the last 28 million years.

19. CONSTRUCTIVE AND DESTRUCTIVE FORCES ON LAND FORMSESS 8.8.4

21. CROWLEY’S RIDGE • CROWLEY’S RIDGE IS A UNIQUE LANDFORM IN NORTHEAST ARKANSAS, RUNNING FROM SOUTHERN MISSOURI DOWN TO AROUND HELENA, ARKANSAS. • The land in that area is relatively flat. • This ridge was formed during the great earthquakes of 1811-1812. • This is the same quake, along the New Madrid fault, that made the Mississippi River change course and even flow backward for a while!

25. swamps • Swamps are low-lying areas, that have standing water in them. • They are very important areas for certain types of animals.

27. canyons

30. Deltas • A delta is a triangular deposit of sediment that forms when a stream or a river slows as it empties into an ocean, gulf, or lake. • Eventually, the Mississippi River reaches the Gulf of Mexico with a tremendous amount of sediment. • The water slows down as it hits the gulf and the sediment spreads out in a triangular shape, forming the Mississippi Delta.

33. TOPOGRAPHIC MAPS • IF YOU WANTED TOI GO HIKING, A CONIC MAP PROJECTION WOULD GET YOU TO THE MOUNTAIN, BUT YOU WOULD NEED A MORE DETAILED MAP SHOWING THE HILLS AND VALLEYS OF THAT SPECIFIC AREA. • A TOPOGRAPHIC MAP SHOWS THE CHANGES IN ELEVATION OF THE EARTH’S SURFACE.

34. TOPOGRAPHIC MAPS • Before starting your hike up the mountain, you would look at the contour lines on your topographic map to see the trails change in elevation. • A contour line is a line on a map that connects points of equal elevation.

35. Topographic maps • The difference in elevation between 2 side by side contour lines is called the contour interval. • If the contour interval was 10 meters, then when you walked between those 2 lines on the trail, you would have climbed or descended 10 meters.

36. Topographic maps • the closer the contour lines are together, the steeper the slope will be. • Contour intervals can be different, but they will be the same distance on that map. • For example, one map may have contour intervals of 5 meters, while another map might have contour intervals of 100 meters.

37. Topographic maps • Some contour lines, called index contours, are marked with their elevation. • If the contour interval is 5 meters, you can tell the elevation of other lines around the index contour by adding or subtracting 5 meters from the elevation indicated on the index contour.

38. Topographic maps • Here are some rules to remember when examining contour lines. • To decide whether you are looking at a hill or basin, you can read the elevation numbers or look for “hachures” • Hachures are short lines at right angles to the contour line that are used to show depressions. • These lines point toward lower elevations.

39. Topographic maps • Contour lines never cross. • Contour lines form v’s that point upstream whenever they cross streams.

44. Agents of Erosion

46. REVIEW • 1. THESE ARE THE LOWLANDS OF THE SOUTHERN UNITED STATES THAT SURROUND THE GULF OF MEXICO. • GULF COASTAL PLAIN • 2. THIS IS A TRIANGULAR DEPOSIT OF SEDIMENT THAT FORMS WHEN A STREAM OR RIVER SLOWS DOWN AND EMPTIES INTO THE OCEAN. • DELTA • 3. THIS TYPE OF MAP SHOWS THE CHANGES IN ELEVATION OF THE EARTH’S SURFACE. • TOPOGRAPHIC • 4. SHORT LINES AT RIGHT ANGLES TO THE CONTOUR LINE THAT ARE USED TO SHOW DEPRESSIONS. • HACHURES • 5. LARGE, RELATIVELY FLAT AREAS OF LAND ARE: • PLAINS • 6. LOW LYING AREAS THAT HAVE WATER STANDING IN THEM AND IS THE HOME OF VERY MANY ORGANISMS. • SWAMP

47. REVIEW • 7. CONTOUR LINES NEVER __________. • CROSS • 8. THE CLOSER THE CONTOUR LINES ARE, THE ___________ THE SLOPE WILL BE. • STEEPER • 9. THIS FLAT, GRASSY AREA LIES BETWEEN THE MISSISSIPPI LOWLANDS AND THE ROCKY MOUNTAINS. • INTERIOR PLAINS • 10. THIS UNIQUE LANDFORM STRETCHES FROM SOUTHERN MISSOURI DOWN TO HELENA, ARKANSAS. • CROWLEY’S RIDGE • 11. SEDIMENTS THAT SLOWLY INCH THEIR WAY DOWN A HILL. • CREEP • 12. LOOSE MATERIALS OR ROCK LAYERS THAT SLIP DOWN A SLOPE IS CALLED ________________ • SLUMP

48. REVIEW • 13. THIS IS A LINE ON A MAP THAT CONNECTS POINTS OF EQUAL ELEVETION • CONTOUR LINE • 14. THIS STRETCHES ALONG THE EAST COAST OF THE UNITED STATES. • ATLANTIC COASTAL PLAIN • 15. THE DIFFERENCE IN ELEVATION BETWEEN 2 SIDE BY SIDE CONTOUR LINES IS CALLED THE __________. • CONTOUR INTERVAL • 16. A THICK MIXTURE OF SEDIMENTS AND WATER FLOWING DOWN A SLOPE. • MUDFLOW • 17. A LARGE MOVING MASS OF ICE AND SNOW IS A _______. • GLACIER • 18. THE TYPE OF EROSION CAUSED BY GRAVITY IS________. • MASS MOVEMENT • 19. VALLEY GLACIERS CAN MAKE A U SHAPED VALLEY OUT OF A V SHAPED VALLEY • TRUE

49. REVIEW • 20. THESE ARE SHALLOW GROOVES LEFT IN ROCK, CAUSED BY A GLACIER DRAGGING BIG ROCKS. • STRIATIONS • 21. THE PROCESS OF BOULDERS BEING LIFTED OUT BY A GLACIER. • PLUCKING • 22. WHEN WIND BLOWN SEDIMENTS STRIKE ROCKS , _____ OCCURS. • ABRASION • 23. THESE HAPPEN WHEN LARGE BLOCKS OF ROCK BREAK LOOSE AND START TUMBLING. • ROCKSLIDES • 24. WIND BLOWS ACROSS LOOSE SEDIMENTS REMOVING SMALL PARTICLES SUCH AS CLAY, SILT, AND SAND.