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- You can figure out the elevation of any point by finding the nearest labeled line, counting the number of lines above or below it, multiplying by the contour interval, and adding or subtracting the result from the nearest marked contour line. The more closely spaced the contour lines, the steeper the slope.
digitalatlas.cose.isu.edu/geog/basics/topo.htm
A topographical map contains curved lines called contour lines. Each contour line corresponds to the points on the map that have equal elevation (Figure 1). A level curve of a function of two variables [latex]f\,(x,\ y)[/latex] is completely analogous to a counter line on a topographical map.
The latitude and longitude coordinates of NRCan maps are found along the edge of a map (for example see the map of Canadian geology we studied in Chapter 1). On USGS topographic maps the latitude and longitude coordinates are found at the corners of the map (Figure 7.2).
- Karla Panchuk
- 2020
Level curves are the equivalent of contours on a topographical map. In such a map the terrain is shown by drawing curves through all points which have the same height above sea level. The numbers on the curves in the map shown below are the heights above sea level in metres.
A contour diagram is, in essence, a \topographical map" of the graph of z = f(x; y). A topographical map is a two-dimensional visualization of three-dimensional terrain through the so-called level curves or contours corresponding to points of equal elevation. Example 1.
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Directions
We are all familiar with the points of the compass (Figure 15.1a), also known as cardinal directions. These allow us to specify general directions, but are insufficient to define specific values. For this we use an azimuth, which is the angle measured clockwise from north (Figure 15.1b). The term bearingis often used synonymously with azimuth, although there are also some other uses of the term, so azimuth will primarily be used here. Therefore, north has an azimuth of 0°, northeast is 45°, e...
Height Datums and Units
When talking about how high a land surface is, we need a reference level, sometimes referred to as the height datum (not to be confused with a geodetic datum, which is an issue that we don’t need to discuss here). Hereafter, we will use the term elevationto define the height above (or, sometimes, below) a height datum. A standard convention in topographic maps is to define elevation relative to the mean sea level (metres above sea level, m a.s.l). In all cases where elevation is involved, be...
Spot Heights and Benchmarks
One of the simplest ways to indicate the elevation of land on a map is to use a spot height, which is simply the elevation of a particular point (e.g. the summit of a hill or mountain). Many spot heights are determined from aerial photographs, rather than being surveyed on the ground. Occasionally, you may also see a benchmark shown on a map. These are points that have been surveyed, perhaps as part of construction projects such as highways or rail lines. Locations that have been surveyed for...
In this lab you will practice 1. Defining direction. 2. Interpreting elevation from contour lines. 3. Calculating slope gradient. 4. Drawing and interpreting topographic profiles. You will need a calculator, plus an internet connection to download a map and access Google Earth. Some of the exercises may be easier if you are able to print the releva...
Figure 15.5 1. Figure 15.5 [PDF] 2. Figure 15.5 [WORD] 3. Figure 15.5 [ODT] Graph paper 1. Lab 15 Graph paper [PDF] Map of Spot Heights at Acme Creek 1. Map of Spot Heights at Acme Creek [PDF] 1. Map of Spot Heights at Acme Creek [WORD] 2. Map of Spot Heights at Acme Creek [ODT]
The scale of map you work with depends on the level of detail you want to show on the map. 5. TOPOGRAPHIC CONTOURS 5.1 Many maps of land areas have series of curved lines, called contours, that represent the topography of the area. Such a map is called a topographic map.Acontour is a horizontal curve that’s the locus of all
3.3 Level Curves and Level Surfaces. Topographic (also called contour) maps are an effective way to show the elevation in 2-D maps. These maps are marked with contour lines or curves connecting points of equal height. Figure 1: Topographic map of Stowe, Vermont, in the US.
