Embedded Files
(How)
"Waterlines on a map of The Isles of Scilly, Ordinance Survey, 1896. From National Library of Scotland" (Vane)
How maps have historically been made
How maps have historically been made
Maps have always been made by using surveying, through a technique called triangulation. Triangulation was done by measuring distances between points and the angles that joined said points (How). This is similar to how surveyor's today do this process, but it is done using electronic devices. Ropes and chains were cut to known lengths and used physical or magnetic compasses to measure the angles. This worked well, but I can assume that these measures would not be accurate depending on the temperature because the molecules within the chain compress when exposed to cold temperatures. I can also assume that over time, when the same rope is used and stretched repeatedly, would increase the distance because over time, the rope will lose its elasticity.
The lower left image is an example of an early map that used contours for terrain and the "water-lining method of representation for water bodies" (Usery). Albert H J Christensen is a man that looked at early western maps and the way in which water is represented in maps. Water can be drawn by using waves, dots, hatching, and waterlines (Vane). You can see what looks like contour lines where there would be water, which is actually what they use to represent water, which is what they call "waterlines."
Works Cited
“How Were Maps Made before Planes and Satellites?” EngineerSupply, 1 Oct. 2021, https://www.engineersupply.com/How-were-maps-made-before-planes-and-satellites.aspx.
Usery, E. Lynn, et al. “125 Years of Topographic Mapping.” Arcnews Online Fall 2009 Issue, https://www.esri.com/news/arcnews/fall09articles/125-years.html.
Vane, Olivia. “I: Drawing Water (in Old Maps).” Observable, 12 Mar. 2021, https://observablehq.com/@oliviafvane/i-drawing-water-in-old-maps.
Topographic Maps
Topographic Maps
When we are looking at topographic maps, we are looking at them in map view, which is looking at the earth downwards from the sky. we can see a few things, the contour lines and the contour interval(s). The contour lines tell us the elevation, when these lines are close together we know that there is a steep change in elevation, and when the lines are far apart, we know that the land there is pretty flat. The contour interval tells us the distance between two interval lines.
Topographic map is a screenshot from the USGS topographic map website
To the left is a topographic map of Apple Valley, CA, this is the area East of Granite Hills High School off of Esaws Avenue. I wanted to show an image of what our local area looks like from a topographic perspective. We can see that our contour interval is 250 ft and our scale is 1 mile, we can see our scale located in the lower right corner of the picture. The highest elevation i can see is located by the 'M' in "Granite Mountains" that is about in the center of the topographic map. This elevation is greater than 5000 ft but less than 5250 ft, i know this because there are two contours past the contour that is labeled 4500 and I know the contour interval is 250 ft.
Page updated
Google Sites
Report abuse