Chapter 2 Sections 2, 3, and 4

Chapter 2 Sections 2, 3, and 4 Landforms and Water; Internal and External Forces Shaping the Earth

Bodies of Water • Hydrologic cycle – the cycle of precipitation, evaporation, and condensation • Aquifer – supply of water between permeable and impermeable rock that can be welled for community water supply http://www.und.edu/instruct/eng/fkarner/pages/cycle.htm

Landforms • Relief – difference in elevation of a landform from lowest point to highest point • Mountains • Hills • Plains • Plateaus

INTERNAL FORCES

Plate Tectonics • Tectonic plates – enormous pieces of earth’s crust, float on top of molten magma • Plates move by spreading (moving apart), subduction (diving under another plate), collision (crashing into one another), and sliding past each other in a shearing motion • Folds – occur where 2 plates meet and cause bending and cracking of the rock • Faults – occur where 2 plates meet, cause a fracture in the earth’s crust, and move past each other

Earthquakes • Caused by grinding and slipping of plates along a fault • Most earthquakes occur along plate boundaries • Side effects – landslides, displacement of land, fires, collapsed buildings, tsunamis • Seismograph detects earthquake presence only • Richter Scale is used to process data from seismograph to determine the relative strength of an earthquake

Volcanoes • Eruptions – hot lava, gases, ash, dust and rocks explode out of vents in the earth’s crust, often creating a hill or a mountain • Majority of active volcanoes, earthquakes and tsunamis – Ring of Fire in Pacific rim (8 major plates) • Hot spots – where the crust is thin and allows liquid, hot magma to melt through

EXTERNAL FORCES

Weathering • Refers to physical and chemical processes that change the characteristics of rock on or near the earth’s surface • Mechanical weathering – ice, plant growth, human activities break rock into smaller pieces • Chemical weathering – elements in the air or water combine with minerals in the rock to create new substances (ex: rust)

Erosion • Occurs when weathered material is moved by water, wind, ice or gravity • Water – widens and deepens streams, form deltas • Waves reduce beaches and build sandbars/islands • Wind – produces sand dunes, sculpted rock, loess • Glaciers – slice out valleys, form moraines (hills), leave eskers (ridges), and create kettles (depressions)

Building Soil • Soil – loose mixture of weathered rock, organic matter, air and water • Humus – composed of only organic material • Fertility – depends on texture and the amounts of humus, air and water • Geographers look at parent material, relief, organisms, climate and time when studying soil • Type of soil in a location is important because it influences vegetation and agricultural potential

Chapter 2 Sections 2, 3, and 4