![]() ![]() The values for latitude are always identified by their position N or S of the equator, and the longitude is identified as E or W of the Prime Meridian. This grid system allows a position on Earth to be uniquely defined with a set of longitude and latitude values. The North Pole has a latitude of 90°N, and the South Pole has a latitude of 90°S. The 0° latitude line is the Earth’s equator, and latitude lines increase up to 90° north or 90° south of the equator. Lines of latitude are imaginary lines that circle the globe parallel to Earth’s equator (Figure 7.1). Source: Karen Tefend (2015) CC BY-SA 3.0 view source Note how the regions defined by two adjacent lines of longitude is narrower as the lines approach the poles of Earth. Figure 7.1 | Latitude and longitude grid system of Earth. Lines of longitude converge as you move north or south of the equator, eventually intersecting at the geographic poles.It may help to visualize longitude lines if you think of an orange, which when peeled will show the sections of orange oriented like longitude lines that section the Earth into segments. Starting with the 0° longitude line (zero degrees, known as the Prime Meridian) that passes through the town of Greenwich, England, the lines of longitude increase to 180° in both directions east and west of the Prime Meridian, meeting at a line of 180° longitude that passes through the Pacific Ocean (Figure 7.1). The longitude is an imaginary line that circles the globe and is oriented so that it passes through the north and south geographic poles. ![]() Geographic coordinates use latitude and longitude to define positions on Earth’s surface. Often geologists will report coordinates of important features using both coordinate systems. UTM coordinates are more accurate and are used in navigation and field work. Latitude and longitude coordinates are used on NRCan and USGS maps they are simpler to interpret and plot on a map than UTM coordinates. There are two coordinate systems commonly used to define positions on Earth’s surface: geographic (latitude and longitude, abbreviated lat/long) and universal transverse mercator (UTM). Any movement to the right or left will be towards the east or west, respectively. Therefore if you move towards the top of the map you are moving in a northerly direction, and if you are moving towards the bottom of the map, you are moving towards the south. The topographic and geological maps produced by Natural Resources Canada (NRCan, which includes the Geological Survey of Canada, GSC), and the United States Geological Survey (USGS) are oriented with north at the top of the map. title: a name that generally describes the location of the map area.north arrow: indicates the direction of geographic north and.scale: this defines the relationship of distances on the map to real distances in the area that the map represents.legend: a guide to the different symbols used on the map, such as lines representing roads and streams.map area or data frame: the part of the map illustrating the map area.Geological maps are maps that illustrate the rock types, rock ages and other geological features of the mapped area. Topographic maps are maps that illustrate the topography (vertical relief, such as hills) of the mapped region. 7.2 MAP PARTS, ORIENTATION, AND SCALEĪ map is a plan view (viewed from above, also known as map view) representation of an area on Earth’s surface. This is a critical skill to prepare students to learn about more complex geologic maps. The purpose of this chapter is to familiarize students with how to read and use topographic maps. Chapter 3 “Topographic Maps” by Karen Tefend and Bradley Deline, CC BY-SA 4.0. (2015) “Laboratory Manual for Introductory Geology”. Prokopiuk (2018) University of Saskatchewan from Deline B, Harris R, & Tefend K. Overview of Topographic Maps 7 Topographic MapsĪdapted by Joyce M. ![]()
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