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Askold Galkin
Askold Galkin

Reading Topographic Maps - Oklahoma Geological ...



Quadrangle maps or quads are a type of topographic map produced by the United States Geological Survey (USGS) that divides the United States into areas or quadrangles bounded by lines of latitude and longitude. These maps have two distinctive features: 7.5-minute length and breadth at a 1:24,000 scale.




Reading Topographic Maps - Oklahoma Geological ...



Between 1947 and 1992, the USGS produced its first 7.5-minute map series, each map covering one-quarter of the previous 15-minute map seriesat the new, 1:24,000 scale. Developing technology enabled cartographers to create detailed maps with even more accuracy. This series of quadrangle maps was generated using newer photogrammetric and aerial photography surveying and mapping techniques. These topographic maps provide valuable tools for many different industries including government, education, scientific research, planning, recreation, and environmental studies.


The USGS released the new generation, 7.5-minute quad maps in 2009, called US Topo, available in digital form and extracted using GIS databases. The integration of GIS data allows these maps to be accessed in traditional map form, including PDFs, and from digital, spatial-data platforms that require specific knowledge - mapping software such as QGIS, ArcGIS, etc. Over time data improves and new layers are added to these maps such as aerial photos, shaded relief, and different feature classifications. USGS continues to update these US Topomaps at regular intervals. The first 3-year production cycle of US Topomaps was completed in 2012, with subsequent editions in 2015 and 2018. The newest edition is expected to be complete by 2021. These 3-year cycles apply to 48 states. Hawaii, Alaska, Puerto Rico, and US Virgin Island are topographically covered at different times and using different scales. Historically, Alaska has only been partially analyzed and is estimated to be mapped completely by 2022.


Many of the maps we create at Muir Way make use of USGS data to showcase topographic terrain in a whole new way. Browse our TOPO Map series of Ski Resorts illustrating their topography in a colorful, simple style based on USGS Quadrant maps. For a more classic look, we have a collection of vintage USGS Topographic maps restored to their original beauty.


In the old days of hiking, everyone learned how to read a topographic map because it was the only option to navigate a hike. Today we have handheld GPS units, GPS watches, and smartphones with GPS. Most new hikers can power their phone on, look at a dot on the map, and figure out their position in a second. And that's great. Until your device doesn't work, and that's where (paper) topographic maps come in. And I know that topographic maps and non-digital navigation can be intimidating, especially for those who never used them. So in this guide, I'm going to focus on the basics of the topographic map so that you can look at one and make sense of it. I'll dive into the deeper subjects of navigation, map & compass, and overland routes in other guides.


Topographic maps translate three-dimensional land features into a two-dimensional (flat) map. You can look at a topographic map and quickly see where the hills, rivers, peaks, and valleys are. When you are navigating, a topographic map can show you where you are, what route to take, and which ways are dead ends.


The first country to be mapped entirely with topographic maps was France in 1789, while in the USA, the U.S. Geological Survey (USGS) just started the process in 1879. The first maps were based on sketches that surveyors made using analog tools to measure distance, angles, and elevations.


It wasn't until the 1930s that aerial photography was incorporated to make the maps more accurate. Today, the USGS doesn't do human surveys anymore but instead uses satellites and drones to update the topographic maps every three years. And as you probably guessed, today's maps are all digital but can still be printed out.


Although topographic maps were originally only printed, today they are available as digital maps or printed. When most people say "bring a topo map with you" they are referring to a paper map. But whether the map is digital or printed, the concepts and how to read the map are the same. I'll talk more about the actual maps that you should use later.


I mentioned earlier that topographic maps were available digitally as well. Digital maps throw a little wrench into the idea of scale. If 1 inch equals 1 mile on a 1:63,360 map, what is 1 inch on a screen? What I can see on 1 inch of a screen on a phone from 2010 is much different then on a high-resolution screen from today. And you can zoom in and out on digital maps too. So how does that all work?


It's basically a matter of detail that's included. For example, Garmin sells 24k (roughly equivalent to a quad topographic map) and the 100k TopoActive maps. The 24k maps include more detail than the 100k maps. But for most free digital maps, the level of detail is as detailed as it can be. And most modern map browsers let you tweak the level of detail on a map or do it automatically for you.


You aren't limited to the maps that that USGS produces when it comes to digital topographic maps (which you can print). Tools like Gaia GPS (discount code here) and CalTopo allow you to view alternate topo maps and print them. You can even customize the maps to include other layers such as snow cover, weather, etc. It's very powerful. Let's look at some of the better digital topographic map options, which you can print out or send to your device.


The best way to really understand a topographic map is to take it with you on a hike, find your position. look at map, look at the features around you, and translate the map features to real-life in real-time. But if you want to practice at home (or when avoiding work), there's a cool trick that you can do with Google Earth that overlays topo maps onto the Earth's contours. It's a great way to prep for a hike and learn topo map features at the same time.


One of the very basics to reading any map is orientation. This topic is fairly controversial amongst my peer group and has caused more than it fair share of needless miles. Personally, I like to keep my North orientation on all maps facing up. It's just the way I was taught as a kid, what I've seen most often throughout my career in construction, surveying, and has just been the norm throughout my circle of influence. This "North" orientation concept comes from the invention of the compass and understanding of magnetic north from early Europeans. Keeping a North orientation is probably most common but truth be told, there's really no wrong or right. Whatever orientation used just needs to be consistent amongst communication.


In modern mapping, a topographic map or topographic sheet is a type of map characterized by large-scale detail and quantitative representation of relief features, usually using contour lines (connecting points of equal elevation), but historically using a variety of methods. Traditional definitions require a topographic map to show both natural and artificial features.[1] A topographic survey is typically based upon a systematic observation and published as a map series, made up of two or more map sheets that combine to form the whole map. A topographic map series uses a common specification that includes the range of cartographic symbols employed, as well as a standard geodetic framework that defines the map projection, coordinate system, ellipsoid and geodetic datum. Official topographic maps also adopt a national grid referencing system.


Other authors define topographic maps by contrasting them with another type of map; they are distinguished from smaller-scale "chorographic maps" that cover large regions,[3][4] "planimetric maps" that do not show elevations,[5] and "thematic maps" that focus on specific topics.[6]


However, in the vernacular and day to day world, the representation of relief (contours) is popularly held to define the genre, such that even small-scale maps showing relief are commonly (and erroneously, in the technical sense) called "topographic".[4]


Topographic maps are based on topographical surveys. Performed at large scales, these surveys are called topographical in the old sense of topography, showing a variety of elevations and landforms.[8] This is in contrast to older cadastral surveys, which primarily show property and governmental boundaries. The first multi-sheet topographic map series of an entire country, the Carte géométrique de la France, was completed in 1789.[9] The Great Trigonometric Survey of India, started by the East India Company in 1802, then taken over by the British Raj after 1857 was notable as a successful effort on a larger scale and for accurately determining heights of Himalayan peaks from viewpoints over one hundred miles distant.[10]


By the 1980s, centralized printing of standardized topographic maps began to be superseded by databases of coordinates that could be used on computers by moderately skilled end users to view or print maps with arbitrary contents, coverage and scale. For example, the federal government of the United States' TIGER initiative compiled interlinked databases of federal, state and local political borders and census enumeration areas, and of roadways, railroads, and water features with support for locating street addresses within street segments. TIGER was developed in the 1980s and used in the 1990 and subsequent decennial censuses. Digital elevation models (DEM) were also compiled, initially from topographic maps and stereographic interpretation of aerial photographs and then from satellite photography and radar data. Since all these were government projects funded with taxes and not classified for national security reasons, the datasets were in the public domain and freely usable without fees or licensing. 041b061a72


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