Chapter 3 Section 1 Notes
Finding Locations on Earth
equator – a circle halfway between the poles that divides the Earth into the Northern and Southern Hemispheres
Latitude
parallels – any circle that runs east and west around Earth and that is parallel to the equator; a line of latitude
latitude – the angular distance north or south from the equator, expressed in degrees
Degrees of Latitude
Measured in degrees
Equator is 0o latitude
The poles are both 90o latitude
1o of latitude is equal to about 111 km
Also known as parallels
Parallels north of the equator are labeled as N
Parallels south of the equator are labeled as S
Minutes and Seconds
minute – each degree of latitude is separated into 60 equal parts
o
symbol (‘)
o
equal to 1.85 km
second – each minute is separated into 60 equal parts
o
symbol (“)
o
each second is about 31 meters
Longitude
meridian – any semicircle that runs north and south around the earth from geographic North Pole to the geographic South Pole, a line of longitude
longitude – the angular distance east or west from the prime meridian; expressed in degrees
prime meridian – a meridian that is assigned 00 and passes through Greenwich, England
Degrees of Longitude
the meridian opposite the prime meridian is labeled 180 0
all locations east of the prime meridian have longitudes between 0 0 and 1800 East and all locations west of the prime meridian have longitudes between 0 0
and 1800 West
Distance Between Meridians
distance between meridians at the equator are 111 km
distance between meridians decreases as you move north or south (Why?)
Great Circles
great circle – any circle that divides the globe into halves or marks the circumference of the globe
equator is the only parallel that is a great circle
all meridians and its opposite are great circles
Finding Direction
geomagnetic poles – areas on Earth’s surface just above where the poles of an imaginary magnet would be
geomagnetic and geographic poles are located at different places
a magnetic compass will point to the geomagnetic poles
Magnetic Declination
angle between the direction of the geographic pole and the direction in which the compass needle points (Fig. 5 page 56)
used to help locate the geographic north and south poles
The Global Positioning System(GPS)
a satellite navigation system that is based on a global network of 24 satellites that transmit radio signals to Earth’s surface
a GPS receives signals from 3 satellites that calculate latitude, longitude and altitude
accurate to within 10 to 15 m of position
Chapter 3 Section 2 Notes
Mapping Earth’s Surface
cartography – science of making maps
cartographer – scientists who make maps
Data collected by field surveys and remote sensing are used to make maps
field survey – make measurements of the area
o
plot information on a map
remote sensing – the process of gathering and analyzing information about an object without physically being in touch with the object
o
satellite images
o
images from airplanes
Map Projections
a flat map that represents a spherical surface
Cylindrical Projection
a cylinder of paper is wrapped around a lighted globe
meridians appear as straight lines
outlines of continents, oceans and parallels are traced
parallels and meridians form a grid
Azimuthal Projection
a sheet of paper is placed on a lighted globe so that only one point of the globe is being touched
little distortion occurs at the point of contact
unequal spacing between parallels causes a distortion in both direction and distance
great help to navigators in plotting routes used in air travel
Conic Projections
placing a paper cone over a lighted globe so that the axis of the cone aligns with the axis of the earth
the cone touches the globe along one parallel of latitude
areas near the parallel are distorted least
polyconic projections – a series of conic projections used to increase the accuracy of mapping a number of neighboring areas
Reading a Map
Directions on a Map
maps are mostly drawn with the top of the map facing north
parallels run from side to side
-
meridians run from top to bottom
compass rose – a symbol that indicates the cardinal directions(north, south, east, west)
Symbols
symbols are used for features on a map such as cities, roads and rivers
legend – a list of map symbols and their meanings
Map Scales
a map must be drawn to scale to be accurate
scale – the relationship between the distance shown on a map and the actual distance
graphic scale – printed line that has markings on it that are similar to those on a ruler
fractional scale – a scale that uses a ratio
Isograms
a line on a map that represents a constant or equal value of a given quantity
used to plot many types of data (i.e., atmospheric pressure on a map)
commonly used to show areas that similar measurements of precipitation, temperature, gravity, magnetism, density, elevation or chemical composition
Chapter 3 Section 3 Notes
Types of Maps
Topographic Maps
one of the most widely used
topographic map – shows the surface features of earth
topography – the size and shape of the land surface features of a region including its relief
shows both natural features and constructed features
shows elevation – the height of an object at sea level
Advantages of Topographic Maps
more detailed information about the surface
shows the size, shape and elevation
Elevation of Topographic Maps
contour lines – a line that connects point of equal elevation on a map
contour lines are isograms that connect points
contour interval – difference in elevation between two contour lines
contour interval is determined by the relief of the land
relief – the difference between the highest and lowest elevations in a given area
index contours – every fifth contour line bolder than the other contour lines
o
makes reading the map easier
Landforms on Topographic Maps
spacing and direction of contour lines indicate the shapes of the landforms represented
widely spaced contour lines indicate change in elevation is gradual
closely spaced contour lines indicates change in elevation is rapid
a “V” shape indicates a valley
o
the bend in the “V” points toward the higher end
o
a “V” indicating a stream or river always points upstream
o
width of the “V” shows the width of the valley
depression is indicated by depression contours – closed-loop lines that have short, straight lines perpendicular to the inside of the loop
Topographic Map Symbols
black – buildings, boundaries, roads and railroads
red – major highways
green – forested areas
purple – information updated by aerial photography but not verified by field exploration
Geologic Maps
designed to show the distribution of geologic forms
geologic maps are created on top of another map called a base map
base map – provides surface features, such as topography or roads usually printed in light colors or as grey lines
Rock Units on Geologic Maps
geologic unit – a volume of rock of a given age range and rock type
geologic units are distinguished by color
assign a set of letters to each rock unit
o
capital letter symbolizes the age of the rock
o
lowercase letters represent the name or the unit or rock type
Other Structures on Geologic Maps
contact lines – indicates places at which two geologic units meet
contact – the actual place where two geologic units meet
o
faults
o
depositional contacts
o
strike – direction in which beds run
o
dip – the angle at which beds tilt
Soil Map
constructed to classify, map and describe soils
based on soil surveys
Soil Surveys
text
o
geology
o
topography
o
climate of the area
tables
o
types of soil
o
volumes of soil
maps
o
approximate location of different types of soil
o
detailed information about the soils in the area
Use of Soil Maps
valuable tools for agriculture and land management
helps identify ways to conserve and use soil and plan sites for future development
Other Types of Maps
location and flow of both water and air
record and predict weather
amount of precipitation
location and direction of the flow of groundwater changes in Earth’s surface over time