Ecology 1130 Earths Surface What Are Topographic Maps

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Ecology 11/30 Earth’s Surface

Ecology 11/30 Earth’s Surface

What Are Topographic Maps? • A topographic map is a type of map that

What Are Topographic Maps? • A topographic map is a type of map that shows elevation. • Topographic maps are used by people like hikers and others who need to know what the elevation of an area is. • So what do these lines mean? Why are there so many, and why are they so crooked?

Contour Lines • Contour lines connect points of equal elevation. All that means is

Contour Lines • Contour lines connect points of equal elevation. All that means is that where there's a line, everything on that line is the same height or altitude. • Think of it this way, if you had a tub of water with a big rock in it and you started filling the tub with water but paused every minute to draw a line where the water had risen to - those lines would be like contour lines. If you did this for the entire rock, then drained all the water out, the rock would have lines all over it. If you looked at this from above, you would see all those lines connecting and forming circles. A topographic map shows those lines. On most maps these lines are shown with a light brown color.

Index Contours • If you were to look at a topographic map, you would

Index Contours • If you were to look at a topographic map, you would realize that there's not just one line, but many. Each line is a different elevation, but some of the lines have numbers on them. These are called index contours. Index contours display the exact elevation of one specific line. • Why not just put numbers on every line? Space. There just isn't enough room on the map to keep putting numbers everywhere, and it would get awfully cluttered if we did.

Example • To put this into perspective, imagine you are somewhere with a big

Example • To put this into perspective, imagine you are somewhere with a big staircase. Maybe you're at the Pyramids of Giza or one of those big concrete sports arenas or any other place where there's lots of steps. Imagine you are at the very bottom of those steps. If you start hiking up the stairs, the tenth step up would be painted light brown. Not just in one spot, the entire step, all the way across. It would represent 10 feet high. This would be one of your contour lines.

Contour interval • The space between any two lines. • Contour interval is the

Contour interval • The space between any two lines. • Contour interval is the distance between any two side-by-side lines. For example, a contour interval of 10 means you would change elevation 10 feet up or down by crossing over those lines on the map. It depends which way you're traveling. • Every space between every line on that map would be 10 feet of elevation change, no matter how close or spread out those lines are. This information will either be printed on the map somewhere or you can figure it out by looking at the index contours.

Contour Rules • One different thing about topographic maps: they have rules. Specifically the

Contour Rules • One different thing about topographic maps: they have rules. Specifically the contour lines have rules - and every topographic map follows them: • 1. Lines cannot cross. • If two lines crossed, it would actually mean that one location had two different elevations. While that would be pretty cool, being at two different elevations at the same time would cause some serious issues with physicists because basically you would need to be in two different places at one time, and that can't happen. • 2. Lines form circles around hills or depressions. • For hills and mountains as you go up in elevation, that circle will get smaller and smaller like a bull's eye.

Lines can (and often do) get really close to each other. The closer those

Lines can (and often do) get really close to each other. The closer those lines, the steeper the hill would be. A sheer cliff would have lines all piled up to show that drastic elevation change, and a gentle slope would have contour lines much more spread out. See how these lines are all bunched up here? This is a topographic map that would represent this type of cliff landform.

Elevation • Elevation, or geometric height, is mainly used when referring to points on

Elevation • Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface.

Relief • Terrain, or land relief, is the vertical and horizontal dimension of land

Relief • Terrain, or land relief, is the vertical and horizontal dimension of land surface. When relief is described underwater, the term bathymetry is used. • Relief (or local relief) refers specifically to the quantitative measurement of vertical elevation change in a landscape. It is the difference between maximum and minimum elevations within a given area, usually of limited extent. [1] The relief of a landscape can change with the size of the area over which it is measured, making the definition of the scale over which it is measured very important. Because it is related to the slope of surfaces within the area of interest and to the gradient of any streams present, the relief of a landscape is a useful metric in the study of the Earth's surface.

Landform • A landform is a natural feature of the Earth's surface. Landforms together

Landform • A landform is a natural feature of the Earth's surface. Landforms together make up a given terrain, and their arrangement on the landscape or the study of same is known as topography. Typical landforms include hills, mountains, plateaus, canyons, valleys, as well as shoreline features such as bays, peninsulas, and seas, including submerged features such as mid-ocean ridges, volcanoes, and the great ocean basins.

Plain • In geography, a plain is a flat area. Plains occur as lowlands

Plain • In geography, a plain is a flat area. Plains occur as lowlands and at the bottoms of valleys but also on plateaus or uplands at high elevations. In a valley, a plain is enclosed on two sides but in other cases a plain may be delineated by a complete or partial ring of hills, by mountains or cliffs. Where a geological region contains more than one plain, they may be connected by a pass (sometime termed a gap). Plains may have been formed from flowing lava, deposited by water, ice, wind, or formed by erosion by these agents from hills and mountains. • Plains in many areas are important for agriculture because where the soils were deposited as sediments they may be deep and fertile, and the flatness facilitates mechanization of crop production; or because they support grasslands which provide good grazing for livestock.

Types of plains • Structural plains: relatively undisturbed horizontal surfaces of the earth. They

Types of plains • Structural plains: relatively undisturbed horizontal surfaces of the earth. They are structurally depressed areas of the world that make up some of the most extensive natural lowlands on the Earth's surface. • Erosional plains that have been leveled by various agents of denudation such as running water, rivers, wind and glacier which wear out the rugged surface and smoothens them. Plain resulting from the action of these agents of denudation are called peneplains (almost plain) while plains formed from wind action are called pediplains. • Depositional Plains formed by the deposition of materials brought by various agents of transportation such as rivers, wind, waves, and glaciers. Their fertility and economic relevance depend greatly on the types of sediments that are laid down. • Depositional Plains are grouped into the following: • Alluvial plains, formed by rivers, and may be one of these overlapping types: • • • Alluvial plain, formed over a long period of time by a river depositing sediment on its flood plain or bed which becomes alluvial soil. The difference between a flood plain and an alluvial plain is that the flood plain represents the area experiencing flooding fairly regularly in the present or recently, whereas an alluvial plain includes areas where the flood plain is now and used to be, or areas which only experience flooding a few times a century. Flood plain, adjacent to a stream, river, lake or wetland that experiences occasional or periodic flooding. Scroll plain, a plain through which a river meanders with a very low gradient. • Lacustrine plain, a plain that originally formed in a lacustrine environment, that is, as the bed of a lake. • Lava plain, formed by sheets of flowing lava. • Glacial plains, formed by the movement of glaciers under the force of gravity: • • Sandur (plural sandar), a glacial out-wash plain formed of sediments deposited by melt-water at the terminus of a glacier. Sandar consist mainly of stratified (layered and sorted) gravel and sand Till plain, a plain of glacial till that forms when a sheet of ice becomes detached from the main body of a glacier and melts in place depositing the sediments it carries. Till plains are composed of unsorted material (till) of all sizes. • Abyssal plain, a flat or very gently sloping area of the deep ocean basin

Mountain Range • A mountain range (also mountain barrier/belt/system) is a geographic area containing

Mountain Range • A mountain range (also mountain barrier/belt/system) is a geographic area containing numerous geologically related mountains. A mountain system or system of mountain ranges, sometimes is used to combine several geological features that are geographically (regionally) related. On Earth, most significant mountain ranges are the result of plate tectonics, though mountain ranges are formed by a range of processes, are found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets. • Mountain ranges are usually segmented by highlands or mountain passes and valleys. Individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology. They may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, and volcanic landforms resulting in a variety of rock types.

Plateau • In geology and earth science, a plateau (/pləˈtoʊ/ or /ˈplætoʊ/; plural plateaus

Plateau • In geology and earth science, a plateau (/pləˈtoʊ/ or /ˈplætoʊ/; plural plateaus or plateaux), also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain that is raised significantly above the surrounding area, often with one or more sides with steep slopes. • Formation • Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Magma rises from the mantle causing the ground to swell upward, in really large, flat areas of rock that are uplifted. Plateaus can also be built up by lava spreading outward from cracks and weak areas in the crust. Plateaus can also be formed by the erosional processes of glaciers on mountain ranges, leaving them sitting between the mountain ranges. Water can also erode mountains and other landforms down into plateaus. Computer modeling studies suggest that high plateaus may also be partially a result from the feedback between tectonic deformation and dry climatic conditions created at the lee side of growing orogens. [1] • Classification[edit] • Plateaus are classified according to their surrounding environment. • Intermontane plateaus are the highest in the world, bordered by mountains. The Tibetan Plateau is one such plateau. • Piedmont plateaus are bordered on one side by mountains and on the other by a plain or sea. • Continental plateaus are bordered on all sides by the plains or seas, forming away from mountains. • Volcanic plateaus are produced by volcanic activity. The Columbia Plateau in the northwestern United States of America is one such plateau. • Dissected plateaus are highly eroded plateaus cut by rivers and broken by deep narrow valleys.

Landform region • A landform region is a specific area that is made up

Landform region • A landform region is a specific area that is made up of the same major landforms, such as plains, mountains or plateaus. Landforms can be described as any natural feature that is on the earth's surface.