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Study Guide- The Earth
-The points of Earth are the geographic North Pole and South Pole.
-Reference grid- used to locate places on the Earth’s surface
-Latitude-describes positions north and south of the equator, expressed in degrees. The
equator is 0 degrees and the North and South Pole are both 90 degrees. These lines are known
as parallel.
-Latitude consists of 60 equal parts called minutes and each minute is divided into 60 equal
parts called seconds
Parallel- any circles that run east and west around earth and parallel to the equator
Longitude- angular distance east or west from the prime meridian, expressed in degrees
Meridian- any semicircle that runs north and south around the earth from the north pole to the
south pole. It passes through Greenwich, England and represents 0 degrees longitude
International Data Line- meridian opposite of the prime meridian, half way around the world, is
labeled at 180 degrees
-The degree of longitude decreases as you move from the equator toward the poles
-Great Circles- circle that divides the earth into halves or marks the circumference on the globe.
Any circle formed by two meridians that are directly across the globe from each other.
-The equator is the only line of latitude that is a great circle.
-The route along a great circle is the shortest distance between two points on a sphere.
-Great circles are used in navigation, such as a plane or boat
-Magnetic declination- the angle between the direction of the geographic pole and direction in
which the compass needle points. In the Northern hemisphere it is measured in degrees east
or west of the north pole. Magnetic declination is always changing. Using this a person can use
a compass to find their direction.
-GPS- Satellite navigation system based on a global network of 24 satellites that transmit radio
signals to Earth’s surface. It is used to calculate the latitude, longitude and altitude of the
receiver on Earth.
-Magnetic compass-indicates direction because Earth has magnetic properties as if a powerful
bar-shaped magnet were buried at Earth’s center at an angle to Earth’s axis of rotation.
-Geomagnetic poles- areas on Earth’s surface just above where the poles of the imaginary
magnet
-The geomagnetic poles and geographic poles are located in different places
-Maps were developed for studying and displaying detailed information about the Earth
-Cartography- science of making maps
-Cartographers- Scientists who make maps. They use data from a variety of sources, such as
field surveys and remote sensing
-Remote Sensing- gathering and analyzing information about an object without physically being
touch with it
- Map- flat representation of Earth’s curved surface. Areas may be distorted in size, shape,
distance or direction
-Map projection- a flat map that represents a a spherical surface. It is not entirely accurate but
has advantages and disadvantages
-Cylindrical projection- a paper is wrapped around the globe and traced outline of continents,
oceans, parallels and meridians. It is most accurate near the equator but distorts distances and
sizes near the poles. It forms a gird which makes locating positions easier.
-Azimuthal projection-projection made by placing a sheet of paper against a globe so that the
paper touches the globe at one point. Little distortion occurs at the point of contact. Unequal
spacing between parallels cause distortion in bothe direction and distance. Advantage is great
circles appear as straight line. Used for plotting navigational paths.
-Conic projection-Placing a paper cone over a lighted globe so the axis of the cone aligns with
the axis of the globe. Areas near the parallel where the cone and globe meet are distorted least.
-Polyconic projection- series of conic projections to increase accuracy by mapping a number of
neighboring areas and fitting the adjoining areas together
-Maps use symbols. They are commonly drawn with north at the top, east at the right, west at
left and south at the bottom. Some use parallels of latitude and meridians of longitude to
indicate direction and location.
-Compass Rose- symbol that indicates the cardinal direction
-Symbols-used to represent features such as cities, highways, rivers and other points of
interest. They resemble the features they represent
-Legend- a list of map symbols and their meanings
-Scale- relationship between the distance shown on a map and actual distance
-Graphic scale- a printed line that has markings that represent units of measure, such as meters
-Fractional scale- a ratio that indicates how distance on Earth relates to distance on a map
-Verbal scale- expresses scale in sentence
Isogram- a line on the map that represents a constant or equal value of a given quanity. Can be
used to plot many data, such as atmospheric pressure, temperature, precipitation, gravity,
magnetism, density, evelation, chemical composition and many others.
-Topographic map- One of the most widely used maps which shows the surface features of
Earth.
-Topography the size and shape of the land surface features of a region
-Elevation the height of an object above sea level.
-Contour line a line that connects points of equal elevation on a map
- Contour interval-The difference in elevation between one contour line and the next. The
contour interval is selected based on the relief of the area being mapped.
-Relief the difference between the highest and lowest elevations in a given area
- Index contour-Every fifth contour line is darker than the four lines one either side of it.
-The spacing and direction of contour lines indicate the shapes of the landforms represented on a
topographic map.
-Closely spaced contour lines indicate that the slope is steep.
-Widely spaced contour lines indicate that the land is relatively level.
-Symbols are used to show certain features on topographic maps.
-Symbol color indicates the type of feature. Constructed features, such as buildings, are Symbol
color indicates the type of feature. Constructed features, such as buildings, are shown in black.
Highways are shown in red. Bodies of water are colored blue, and forested areas are colored
green.
-Contour lines are brown or black.
-Geologic maps- designed to show the distribution of geologic features, such as the types of
rocks found in a given area and the locations of faults, folds, and other structures.
-On geologic maps, geologic units are distinguished by color. Units of similar ages are generally
assigned colors in the same color family, such as different shades of blue.
-In addition to assigning a color, geologists assign a set of letters to each rock unit. This set of
letters symbolizes the age of the rock and the name of the unit or the type of rock.
-Contact lines-Other markings on geologic maps are contact lines. They indicates places at which
two geologic units meet, called contacts.
`2 main types of contacts
-Faults
-Depositional contacts.
-Strike- indicates the direction in which the beds run.
-Dip indicates the angle at which the beds tilt.
- Soil maps- Scientists construct soil maps to classify, map, and describe soils, based on surveys
of soils in a given area.
- Soil survey- consists of three main parts: text, maps, and tables. Includes general information
about the geology, topography, and climate of the area. The tables describe the types and
volumes of soils in the area. The maps show the approximate locations and types of the different
soils.
-Soil maps are valuable tools for agriculture and land management. They are used by farmers,
agricultural engineers, and government agencies.The information in soil maps and soil surveys
helps developers and agencies identify ways to conserve and use soil and plan sites for future
development.