Exam Review Part 3- Deserts, Glaciers, and maps
What causes a desert?
Lots of sand Vegetation holds the arms
Star Dunes- Star dunes form only in places where wind blows from varied directions over the course of a year. Star dunes have three or more arms, formed from multiple wind directions.
The Sahara - The biggest desert in the world The Nile is the only river that carries water all year long. The desert reaches from the Atlantic Ocean in the west to the Red Sea in the east There are about 90 bigger oases in the Sahara desert, where water comes up from underground rivers or wells. People here live in small villages and grow crops. The Sahara also has important raw materials. Oil and gas lie under the Algerian and Libyan desert. There are also other minerals, like copper and iron ore. The Sahara was not always a desert. During the Ice Age, when many parts of the world were covered with snow and ice, northern Africa had a much wetter climate. In desert oases people can live the whole year. They grow dates, wheat and other crops. But, they must also fight against sand storms and wandering dunes that threaten to cover the oases with sand.
Light breezes can carry the smallest particle= DUST Only strong winds can carry sand particles Moderate winds tend to roll or slide sand along
Wind rarely carries anything larger than sand Wind erodes dry material, not wet soil (which tends to stick together)
Wind as a Transport Agent Factors in how wind carries things wind strength particle size surface material
Wind as an Agent of Erosion: Rounded and Frosted Grains of Sand
Glaciers Glaciers form where more snow falls in winter than melts in the summer.
Glaciers = Huge amounts of fresh water Melting Glaciers (in summertime) = fresh water to rivers = drinking water for a number of areas examples: Norway, Switzerland, Alaska, Washington State, parts of Canada, Bolder Colorado which is a source for hydroelectric power
When glaciers reach 100 ft thick the weight causes them to move or flow. Large amounts of rock and soil are pulled along
End Moraine = rock and soil piled up at the end of a melting glacier Outwash = material carried further by melted glacier water
When glaciers reach water, pieces break off causing ice bergs in a process called calving
TYPES OF GLACIERS Valley Glaciers Piedmont Glaciers
ICE CAP GLACIER CONTINENTAL/ ICE SHEET Small domed shaped
Melting Ice Sheets
Melting Glaciers = if all melt = the oceans will rise approx 130 feet, some cities will go under
1938 1998 1981 2009
Muir Glacier - Alaska
In the past 125 years= the Athabasca Glacier Retreat
As the glaciers melt, weight is reduced on the continental crust and uplifting occurs = Isostatic Rebound
OTZI 5000 year old Iceman, found in 1991 Scientists have poked, prodded, and x-rayed the 5,000-year-old mummy found in the Alps
he was murdered OTZI
Maps
Elevation Representation A topographic map shows elevation Contour lines are lines that connect points of equal elevation. sea level starts at ZERO
Topo Maps are color coded: BROWN/ Black: Contour Lines of Elevation WHITE: Area of No Vegetation GREEN: Vegetation (Forests, Grasslands) BLUE: Water (Sea, Ocean, Lake, River, Pond)
BLACK: Man-Made Features (Buildings, Roads, Mines) RED: Significant Manmade Features (Highway, Government Area) PINK: Densely Populated Urban Area
RULES
RULES Small dashed lines= depression Contour lines point up hill= water flows in opposite direction
Look over the map examples and be able to apply what you know to answer some questions about these types of maps