Download Mapping Ch. 2

Earth Science
Unit 1 Chap. 7 Lecture Notes
B. Rife
page 1 / 6
Chapter 7 Using Maps
HOMEWORK:
HW 1
HW 2
Topic Questions: PG. 114, 117, 120, 123
Review, Interpret & Apply, Crit. Thinking pg 126-7
Unit 1 Map projections, Location, Scales
Topic 1 Making Accurate Map Projections
A MODEL IS A REPRESENTATION OF AN ACTUAL OBJECT, OR AN IDEA OF HOW
AN OBJECT LOOKS.
OBLATE SPHEROID - IS A SPHERE THAT BULGES AT THE EQUATOR AND
FLATTENED AT THE POLES: THE SHAPE OF THE EARTH.
A SCALE MODEL REPRESENTS A REAL OBJECT REDUCED IN SIZE.
A GLOBE IS THE BEST EARTH MODEL BECAUSE ITS SHAPE IS SIMILAR TO
EARTH'S. BUT GLOBES ARE NOT CONVENIENT TO USE.
A MAP PROJECTION IS THE CURVED SURFACE OF EARTH REPRESENTED ON A
FLAT PIECE OF PAPER.
MERCATOR PROJECTION - A FLAT REPRESENTATION OF EARTH IN WHICH
LINES OF LATITUDE AND OF LONGITUDE ARE PARALLEL
SEE FIG. 7.2 PG. 110
GNOMONIC PROJECTION - IS MADE AS IF A PAPER WERE LAID ON A POINT ON
EARTH’S SURFACE
POLAR PROJECTION - A FLAT REPRESENTATION OF EARTH IN WHICH
LONGITUDE LINES EXTEND OUTWARD FROM THE POLES, AND LINES OF
LATITUDE APPEAR AS CIRCLES.
POLYCONIC PROJECTION - IS SOMETIMES USED TO PRODUCE ACCURATE
MAPS OF SMALL AREAS. ROAD AND WEATHER MAPS.
Topic 2 LATITUDE: DISTANCE NORTH & SOUTH
GEOGRAPHIC GRID - COMPLETE NETWORK OF PARALLELS AND MERIDIANS
ON THE SURFACE OF THE GLOBE, USED TO FIX LOCATIONS OF POINTS.
PARALLELS OF LATITUDE - SMALL CIRCLES PRODUCED BY PASSING PLANES
THROUGH EARTH PARALLEL WITH PLANE OF EQUATOR.
Earth Science
Unit 1 Chap. 7 Lecture Notes
B. Rife
page 2 / 6
LATITUDE - ANGULAR MEASURE OF DISTANCE IN DEGREES NORTH OR SOUTH
OF THE EQUATOR.
THE EQUATOR IS A GREAT CIRCLE * NUMBERED 0 DEGREES LATITUDE.
Topic 3 LONGITUDE: DISTANCE EAST AND WEST
MERIDIANS OF LONGITUDE - HALVES OF GREAT CIRCLES *, ENDING AT
EITHER POLE. (* TOPIC 4)
LONGITUDE - ANGULAR MEASURE OF DISTANCE IN DEGREES EAST OR WEST
OF PRIME MERIDIAN.
PRIME MERIDIAN - DESIGNATED REFERENCE MERIDIAN OF ZERO LONGITUDE.
GREENWICH MERIDIAN IS UNIVERSALLY ACCEPTED.
INTERNATIONAL DATE LINE - THE 180 DEGREE MERIDIAN OF LONGITUDE,
FORMING THE BOUNDARY BETWEEN ADJACENT TIME ZONES THAT ARE
12 HOURS SLOW AND 12 HOURS FAST WITH RESPECT TO GREENWICH
STANDARD TIME.
ONE DAY IS LOST GOING WEST, AND ONE DAY IS GAINED GOING EAST
ACROSS THE INTERNATIONAL DATE LINE.
TOPIC 5 MAP SCALES
THE SCALE - IS A FIXED RATIO BETWEEN THE SIZE OF THE MODEL AND THE
SIZE OF THE REAL OBJECT.
REPRESENTED: 1. VERBALLY - ONE INCH TO 100 MILES
2. GRAPHICALLY - LINE DIVIDED INTO UNITS
3. NUMERICALLY - 1 : 24,000
SMALL SCALE - MORE AREA, LESS DETAIL
LARGE SCALE - LESS AREA, MORE DETAIL
UNIT 2 PARTS OF A TOPOGRAPHIC MAP
TOPIC 6 SHOWING ELEVATION
TOPOGRAPHY DESCRIBES THE SURFACE FEATURES OF AN AREA.
Earth Science
Unit 1 Chap. 7 Lecture Notes
B. Rife
page 3 / 6
TOPOGRAPHIC MAPS SHOW THE TOPOGRAPHY OF AN AREA IN DETAIL.
THESE MAPS SHOW THE LOCATION, LANDSCAPE, AND CULTURAL
FEATURES OF A SMALL PART OF EARTH'S SURFACE.
THE MOST OUTSTANDING FEATURE OF A TOPOGRAPHIC MAP IS THAT IT
SHOWS THE ELEVATION, OR HEIGHT OF VARIOUS FEATURES ON THE
MAP. A
TOPOGRAPHIC MAP IS A THREE-DIMENTIONAL MODEL OF AN AREA.
A CONTOUR LINE IS DRAWN ON A MAP TO JOIN ALL POINTS OF THE SAME
ELEVATION.
SEA LEVEL HAS ZERO ELEVATION.
ELEVATION IS THE DISTANCE ABOVE OR BELOW SEA LEVEL.
CONTOUR INTERVAL - THE DIFFERENCE IN ELEVATION BETWEEN TWO
ADJACENT CONTOUR LINES.
CONTOUR INTERVALS ARE USUALLY GIVEN IN MULTIPLES OF FIVE. THE SIZE
OF THE INTERVAL DEPENDS ON HOW MUCH THE ELEVATION CHANGES
IN THE AREA MAPPED.
RELIEF - DESCRIBES HOW MUCH VARIATION IN ELEVATION AN AREA HAS.
RUGGED OR HIGH RELIEF HAS GREAT VARIATION IN ELEV.
RUGGED MOUNTAINS OR CANYONS HAVE LARGE CONTOUR INTERVALS.
SEASHORES AND FLAT PLAINS HAVE SMALL CONTOUR INTERVALS.
FIVE GENERAL RULES IN STUDYING CONTOUR LINES ON A MAP:
1. CONTOUR LINES CLOSE (CONNECT) AROUND HILLS, BASINS, OR
DEPRESSIONS. (TOPIC 11)
HACHURES ARE SHORT LINES PLACED AT RIGHT ANGLES TO THE CONTOUR
LINE, AND THEY ALWAYS POINT TOWARD THE LOWER ELEVATION.
(TOPIC 7 DEPRESSION CONTOURS)
2. CONTOUR LINES NEVER CROSS CONTOUR LINES OF A DIFFERENT
ELEVATION.
Earth Science
Unit 1 Chap. 7 Lecture Notes
B. Rife
page 4 / 6
3. CONTOUR LINES APPEAR ON BOTH SIDES OF AN AREA WHERE THE SLOPE
REVERSES DIRECTION.
4. CONTOUR LINES FORM V's THAT POINT UPSTREAM WHEN THEY CROSS
STREAMS.
5. ALL CONTOUR LINES EITHER CLOSE OR EXTEND TO THE EDGE OF THE
MAP.
TOPIC 8 BENCH MARKS, SPOT ELEVATIONS
A BENCH MARK POINT IS A LOCATION WHOSE EXACT ELEVATION IS KNOWN
AND NOTED ON A BRASS PLATE.
BENCH MARKS ARE SHOWN ON MAP BY THE LETTERS BM ELEV.
TOPIC 9 U.S. GEOLOGICAL SURVEY MAPS
THE UNITED STATES GEOLOGICAL SURVEY (USGS)PRODUCE TOPOGRAPHIC
MAPS OF THE ENTIRE COUNTRY.
ONE SERIES OF QUADRANGLES IS CALLED THE 7.5 MINUTE QUADRANGLE
SERIES. THE SCALE OF MOST OF THESE MAPS IS 1 : 24,000
(1 INCH = 2,000 FEET)
THE KENAI RIVER REC. MAP SCALE IS 1 : 25,000 (1 INCH = 2,083 FEET)
THE ALASKA STATE MAP SCALE IS 1 : 2,500,000
(1 INCH = 208,333 FEET = 39.5 MILES)
Earth Science
Unit 1 Chap. 7 Lecture Notes
B. Rife
page 5 / 6
UNIT 3 READING A TOPOGRAPHIC MAP
TOPIC 10 READING THE CONTOUR MAP
A LEGEND EXPLAINS EACH SYMBOL USED ON THE MAP. PG 666-667
BLUE REPRESENTS WATER: RIVERS, LAKES
GREEN IDENTIFIES FORESTED VEGETATION
MAGNETIC DECLINATION IS THE DIFFERENCE IN THE ANGLE BETWEEN TRUE
NORTH AND MAGNETIC NORTH. IT MUST BE KNOWN PRIOR TO ANY MAP
CALCULATIONS.
TOPIC 11 LAND FORMS ON CONTOUR MAPS
NOTE TOPOGRAPHIC (GEOLOGIC) FEATURES USING A TOPOGRAPHIC MAP.
HILL TOPS, RIDGES, VALLEYS, CLIFFS
TOPIC 12 THE AVERAGE SLOPE
THE AVERAGE SLOPE OR GRADIENT, BETWEEN ANY TWO POINTS CAN BE
DETERMINED.
CHANGE IN ELEVATION
RISE
AVERAGE SLOPE =
CHANGE IN DISTANCE =
RUN
GRADE IS DETERMINED PER HUNDRED UNITS
=
8 FT
100 FT = 8%
TOPIC 13 PROFILE FROM CONTOUR MAPS
A PROFILE SHOWS THE UPS AND DOWNS (SLOPE OR GRADIENT) OF A LINE
ACROSS ANY PART OF A CONTOUR MAP.
PLOTTING IS EASIER ON GRAPH PAPER IF THE VERTICAL IS STRETCHED OUT.
(EXAGGERATED)
VERT.
ELEV.
(UNIT)
HORIZONTAL DISTANCE (UNIT)
UNIT 4 MODERN METHODS OF MAPMAKING
TOPIC 14 REMOTE SENSING
Earth Science
Unit 1 Chap. 7 Lecture Notes
B. Rife
page 6 / 6
TODAY, MOST MAPS ARE MADE BY REMOTE SENSING, GATHERING DATA
ABOUT THE LAND FROM ABOVE THE SURFACE.
PHOTOGRAMMETRY - AERIAL PHOTOGRAPHY FROM PLANES OR SATELLITES.
IMAGING RADAR - CAN BE USED WHEN THE SURFACE IS DARK OR HIDDEN BY
CLOUDS.
TOPIC 15 COMPUTER IMAGING
LANDSAT - SATELLITE (700 KM) IMAGES DETECT WAVELENGTHS IN GREEN,
BLUE, & RED VISIBLE AND INFRARED (HEAT)
FALSE COLOR IMAGES CAN BE USED TO INDICATE ANY DIGITIZED FEATURE.
TOPIC 16 USES OF COMPUTER-DRAWN MAPS AND IMAGES
GEOGRAPHIC INFORMATION SYSTEMS (GIS)
FARMING, NATURAL RESOURCES (FORESTRY),
WATER & AIR POLLUTION
MILITARY, ARCHAEOLOGY