I. Earth Structure Itself A. Made of several layers
1. Inner Core
a. about 1200km at the center of the Ea.
b. very hot, under a lot of pressure
c. mostly Fe, Ni metals, very dense, 12.7-13.0 g/cm3 d. solid in nature
2. Outer Core
a. about 2250km thick
b. liquid in nature
c. made from Fe, Ni
3. Stiffer Mantle
a. assumed to be solid
1) more likely to be a stiff gel like substance
2) half liquid / half solid
b. density 3.3-5.5 g/cm3 c. tectonic plates subduct into this area
4. Asthenosphere
a. other name = plastic mantle
1) very much a semi-solid at melting point
2) think of warm candle wax, moldable, pliable when warm
3) convection currents occur here
(a) warm rises, cool sinks
(b) causes tectonic plates to move over Earth’s surface
5. Crust
a. Very thin compared to other layers
b. ranges from 10-65km thick
1) 10km below oceans
2) 65 under inner continents
c. part of the lithosphere
6. Lithosphere
a. the crust and upper section of the asthenosphere
b. solid, rock like, stiff
c. litho – means stone
1) interest idea: lithography (art) ( advertising)
7. Temperature
a. decrease until 20m mark
b. below 20m, temps raise1degree/40m
c. heat comes from radioactive materials (U,Th,K)
See ESRT pg 10, Inferred Properties of Earth’s Interior. know how to read and identify information.
8. Earth’s overall shape
a. slightly bigger at the equator than at the poles
1) circumference @ equator 40,074 km
2) circumference @ poles 40,007 km
3) this size difference is only a hair when considering the relative size
b. the Earth still looks like a perfect circle from space
c. note diameter of Earth on ESRT on the Astronomy Table II. Latitude and Longitude A. Grid like system with coordinates to locate places on Earth accuratley
III. Topography and Topographic Maps
III. Topography and Topographic Maps A. Land can be shown a 2 dimensional map by using lines and symbols
B. Topography Maps
1. show relief, ups and downs of the land
2. quadrangles- maps of an area broken down into sections
a. Adirondack quadrangles
3. Symbols and items of a map
a. map scale: shows relative distances to scale
(1) measures distance in ratio 1:24 000 means 1” = 24,000’
(2) watch measurement lines – be careful
b. contour lines
(1) interval is identified
(2) usually brown
(3) close together means steep slope
(4) far apart means gradual slop
c. depression contours
(1) contour line with hatch marks on it
(2) shows a dip in land
d. bench mark
(1) measured elevation at a particular time
(2) land does continue to rise and fall after measurement
e. magnetic declination
(1) show direction of true north in relation to magnetic compass
(2) very precise travel (airplanes, satellite pictures etc)
would need to take this into account in calculations
4. Gradient
a. also known as slope
gradient = change in elevation between to 2oints (field value) (ft) distance between 2 points (mi) b. identifies how steep a relief is
note equation on front page of ESRT!! 5. profile
a. a sideway picture of an area
b. draw using contour lines and map scale