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