Lesson 8 Flashcards
Can be defined as the shape, configuration, roughness or three-dimensional quality of Earth’s surface
Topography
Are made to show this information, together with the location of artificial and natural features of the Earth, including buildings, highways, streams, lakes, forests and so on.
Topographic maps
Provide much definite and exact information which can be used as a basis for various purposes.
Detailed topographic maps
7 Different Methods in Representing Relief
Spot Heights or Spot Elevations
Hachures
Form Lines
Contour Lines or Isohypses
Layer Tinting System
Shading
Relief or Terrain Models
Provide definite and precise information regarding elevation.
Spot Heights or Spot Elevations
Are heights of places surveyed and they denote the actual height above mean sea level. They are shown in maps as dots with their respective values written beside it.
Spot Heights or Spot Elevations
The elevation of important features and critical points such as road junctions, peaks, summit, sags, and highway crossings are indicated on the map.
Spot Heights or Spot Elevations
Are series of short lines drawn in the direction of the slope.
Hachures
The lines are heavy and closely spaced
Steep slope
The lines are fine and widely spaced.
Gentle slope
Only give a general impression of the configuration of the ground, but they do not provide numerical values such as the actual elevations of the ground surface.
Hachures
Are drawn when not enough vertical control is available or when the surface is too irregular or intricate contour.
Form lines
Are usually represented as dashed lines and do not portray any actual elevations.
Form lines
They are only used to show the shapes of terrain rather than relief.
Form lines
This is the most widely used method of quantitatively representing hills, mountains, depressions, and ground surface undulations on a two-dimensional sheet of paper.
Contour Lines or Isohypses
Are shown on maps as the traces of level surfaces of different elevations.
Contour Lines or Isohypses
A topographic map containing contour lines shows not only the elevations of points on the ground, but also the ______
Shape of the various topographic features
It is common use for aerial navigation charts and on small scale maps of the world.
Layer Tinting System
Used to show different zones of elevations.
Scale of graded color tints or a system of different colors
_____ when used in conjunction with contour lines give pictorial effect by accentuating the areas of different elevations.
Color tints
An old method use to show relative elevations on maps.
Shading
It is dependent upon shadow cast by the elevated portions of the land.
Shading
This method is accomplished by correct placement on the map of different shades of gray tints.
Shading
Provide the most striking and realistic expression of topography.
Relief or Terrain Models
The model is a representation of the terrain done in three dimensions to suitable horizontal and vertical scales.
Relief or Terrain Models
It is in fact a miniature of the terrain it represents.
Relief or Terrain Models
They are made from wax, clay plastic, cardboard, or other materials and shaped to agree with the actual terrain.
Relief or Terrain Models
It is widely used as teaching aids in geography and geology courses and also used in public exhibits.
Relief or Terrain Models
Universal method to show the relief.
Contour
The unit of measurement of contour is _____
Meters above the mean sea level
Has an advantage that it does not hide the other features drawn on the toposheet.
Contour
A skill that helps us to understand the actual landscape.
Reading contours
Contours are drawn at regular intervals in ________
Brown colour
Generally 20m interval is followed in ______ and _______ in 1:250,000 toposheet.
1:50,000
50m interval
Every _______ is a dark line to enhance map reading.
Fifth contour
The ______ is printed by breaking the contour line and also given at the edge of the toposheet.
Value of contour
Generally contours never cut or cross each other. In case of water fall and cliffs contours almost touch a same point or a line. In overhanging cliff the contours ________
Cut each other
The vertical distance between adjacent contour lines.
Contour interval
A line connecting points of equal elevation. It may be marked with its elevation in feet above sea level.
Contour line
The vertical distance of a point above a reference plane. On a topographic map, the plane is usually mean sea level.
Elevation
The distance in elevation between the top of an object (a hill, tower, etc.) and its base.
Height
The difference in elevation between the highest point and the lowest in an area, or as shown on a topographic map.
Relief
A map showing the shape of the land surface. Commonly it also depicts forests, grasslands, and cultural features like communities, highways, and railroads.
Topographic map
The set of physical features - mountains, hills, valleys, and other landforms- that characterizes a landscape.
Topography
A point or small area of high ground. When you are on a hilltop, the ground slopes down in all directions.
Hill
A line of high ground with height variations along its crest.
Ridge
Reasonably level ground bordered on the sides by higher ground. Contour lines indicating a _____ are U-shaped and tend to parallel a stream before crossing it. The course of the contour line crossing the stream always points upstream.
Valley
A dip or low point along the crest of a ridge.
Saddle
A low point or hole in the ground, surrounded on all sides by higher ground.
Depression
Similar to a valley, except that it normally is a less developed stream course in which there is generally no level ground and, therefore, little or no maneuver room.
Draw
Are caused by flash floods and can be found on flat terrain but are more often found along the sides of ridges. Contour lines indicating a _____ are shaped like a “V” with the point of the “V” toward the head of the draw (high ground).
Draws
A usually short, continuously sloping line of higher ground, normally jutting out from the side of a ridge.
Spur
Is often formed by two thoroughly parallel streams cutting draws down the side of a ridge
Spur
A vertical or near-vertical slope. The ticks always point toward lower ground.
Cliff
Five Different Types of Contours
Index Contours
Intermediate Contours
Depression Contours
Supplementary/ Auxillary Contours
Approximate Contours
A contour is shown by heavier line at regular intervals on a topographic maps.
Index Contours
They are usually drawn every 5th contour and carry the contour number or elevation designation.
Index Contours
The four lighter weight contours found between the index contour.
Intermediate Contours
In a certain portion of the map where the intermediate contours are so closely spaced as they nearly unite or merge into a single line. It is standard practice for readability not to portray the line for short distances. This technique is called ________
Feathering
Are drawn to show low spots as excavations around which contour close.
Depression Contours
They are drawn as dashed lines or lines that begin and end when they approach the areas where the regular contours close in on each other.
Supplementary/ Auxillary Contours
In some instance, contour accuracy cannot be definitely determined. The area may be inaccessible on the ground or it may be difficult to interpret contours from aerial photographs when heavy cloud or shadow occurs to portray reasonable idea o relative elevations, the map markers has to make an educated guess rather than have a blank area in the map.
Approximate Contours
Every point on the same contour line has the same elevation.
Every contour closes on itself, either within or beyond the limits of the map.
Contour Characteristics
A contour which closes within the limits of the map indicates a summit or a depression. Contours which increase in elevation represent hills; those which decrease in elevation portray valleys or excavations.
Contours on the ground cannot cross one another except where an overhanging cliff, a vertical ledge or wall is represented on the map.
Contour Characteristics
Contours are straight and parallel to each other on a plane surface.
Irregular contours signify rough, rugged terrain.
Contour Characteristics
Irregular contours signify rough, rugged terrain.
The horizontal distance between adjacent contours indicates the steepness of the slope of the ground. Where the contours are relatively close together, the slope is comparatively steep; where the contours are far apart, the slope is gentle.
Contour Characteristics
Contours cross curbs and crowned sloping streets in typical U-shaped curves.
Contour lines form a V pattern when crossing streams. The apex of the V always points upstream (uphill).
Contour Characteristics
The time and expense of field and office work is given important consideration. The smaller the interval, the greater is the amount of field work, reduction, and plotting required in the preparation of the map. The cost of the map will be higher as the contour interval is reduced.
RELATIVE COST
Close contouring will be required when the map is to be utilized for the detailed design of engineering construction or for the measurement of earthwork quantities. A wider interval will be required for surveys of reservoirs, drainage areas, and lines of communication.
PURPOSE OF THE MAP
Rugged terrain will require a larger interval than gentle and rolling country. To portray adequately flat ground a relatively small interval must be specified.
NATURE OF THE TERRAIN
The contour interval should be in inverse ratio of the scale of the map. If the map is reduced, the interval must be increased; otherwise line are crowded, confuse the map user, and may possibly obscure some important map details.
SCALE OF THE MAP
In the design of topographic maps, the contour interval is commonly fixed at multiples of ______
0.5, 1, 2, 5, 10, 20, 50, and 100 meters.
For general types of terrain, the contour interval used maybe as follows:
Flat to gently rolling:
Hilly:
Mountainous:
1 to 5 meters
5 to 20 meters
25 to 100 meters
A representation of the earth’s surface and most of its features such as roads, buildings, vegetation, etc. To identify these features on a map, they are represented by symbols and colors.
Map
A cross-sectional view along a line drawn through a portion of a topographic map.
Profile
