Topography the natural and human features of the Earth s surface. ie. Surface features need to understand difference between relief and elevation

Transcription

1 Chapter 1 Landform Patterns and Processes Highlighted script will not be assessed Topography the natural and human features of the Earth s surface. ie. Surface features need to understand difference between relief and elevation Elevation - the height of a particular point of land above sea level Relief - the change in elevation over a given distance Hill areas of high relief with elevations no higher than m isolated features Mountain areas of high relief with elevations higher than m most occur in long linear chains called ranges (usually along margins of continents) Plain a level tract of land frequently found along coastal areas or at lower elevations very gentle slope and no local a relief for thirty metres or more Plateau an extensive, relatively flat upland area have been raised upward into higher elevations by movements of the Earth s crust often found in interiors of continents because they are often deeply eroded by stream valleys, they have more rugged appearances than plains

2 The Structure of the Earth Core Inner Core deepest part of the earth (1512 miles deep) solid that contains both iron and nickel is a magnet, a compass Outer Core (1419 miles deep) similar to the inner core but it is a liquid (contains sulphur and oxygen which lowers the melting point) Mantle Occupying 1789 miles magma (iron and magnesium) that makes up the mantle mostly solid except the outer Km which is extremely hot and goopy; very plastic-like outermost liquid layer of the mantle is referred to as the asthenosphere Lithosphere (Crust) the crust and that upper layer of the mantle which lies above the asthenosphere basically hardened mantle (magma) contains two segments, the oceanic and continental crusts

3 Compressional force a force pushing into a part of the earth s crust, causing it to buckle plates move towards one another, squeezing together subduction zones sometimes form along these areas Tensional force a stretching force in the earth s surface which may cause faulting plates break apart, moving away from or past each other, which may form a trench as one plate drops downward ridge zones sometimes occur where two plates move apart. Magma may rise between the plates and form a ridge

4 Mountain Building Fold mountains an upland area formed by the buckling of earth s crust. Many fold mountains are associated with destructive or collision margins of plates. amount and extent of force and pressure, can create simple or complex forms. Anticline an arch-like upfold in buckled, bent, or contorted rock. looks like the letter A Syncline a downfold of rock layers. looks like a S mile Mountains formed by faulting Normal Fault a fault in which rocks have moved down the slope of the fault two normal faults occur parallel to each other, with plate in-between dropping down as plates move away from each other - forms rift valley land between two parallel faults rises - forms block mountain

5 Reverse Fault a fault, perhaps caused by a compressional force, where movement is up, rather then down, the face over which movement occurs. Overthrust Fault occurs when a plate that undergoes faulting has already experienced folding and its folded layers are then pushed up and thrust over layers on the faults other side.

6 Mountains formed by Volcanoes Along plate boundaries, heat is generated because of friction, pressure, and decay of radioactive materials. Intense heat melts rock beneath the crust producing magma If it reaches surface - through fractures or vents, extrusive volcanic activity takes place. Terms Lava - liquid rock Ash (cinder) - small molten rock fragments Vent - Single opening through which the volcanic products erupt Mild volcanic eruptions thin, liquid lava flows small amounts of gas Explosive volcanic eruptions thick lava flows large quantities of gas, ash and cinders why? - thick lava hardens quicker - plugs up - and then must be exploded out Three types of Volcanic Cones Ash and Cinder Cone eruptions consist mainly of ash and cinders thick, slow flowing, rapidly solidifying lava shape is symmetrical steep sides large crater

7 Shield Cone usually milder eruption little or no ash and cinders very thin, liquid lavas broad, flat cones Composite Cone undergoes periods of both explosive and quiet activity layers of ash and cinders intermixed with layers of lava weak spots may develop on sides with smaller lava flows forming smaller craters Complete Reproducible Worksheet 1.6