![]() ![]() Accessing the information you need is easier and quicker than ever. Filters and searches work seamlessly with the map records table to get you the info you need with fewer clicks. ![]() We've added the ability to preview maps within the interface and give you tools to compare any historical map with maps of the present. The latest version of topoView is full of enhancements based on hundreds of your comments and suggestions. New functionality driven by your feedback Like the historical topographic mapping collection, we've added a variety of file formats previously unavailable for the US Topo series, including GeoTIFF and KMZ. Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which is usually mean sea level. As the Earth rotates, one would ideally expect to find a high tide. The US Topo series is a latest generation of topographic maps modeled on the USGS historical 7.5-minute series (created from 1947-1992). The distinctive characteristic of a topographic map is the use of elevation contour lines to show the shape of the Earths surface. significantly by tides, but also with the elevation of lake and river surfaces. The closer together the inclines, the steeper the hill. Think of contour lines as the distance between each incline. When contour lines are closer together on a map, they indicate a steep slope. Topographic maps show the three-dimensional shape of the land and features on the surface of the earth. We've added the US Topo series to topoView, giving users access to over 3 million downloadable files from 2009 to the present day. 1 Answer Katie Contour lines are used in a map to portray differences in elevation. A topographic map (like the one in figure 1) is one type of map used by geologists. The NGMDB project is proud to assist the NGP in bringing these maps to the Web. Geologic and topographic mapping have a long tradition together (see 1888 report). This interface was created by the National Geologic Map Database project (NGMDB), in support of the topographic mapping program, managed by the USGS National Geospatial Program (NGP). TopoView shows the many and varied older maps of each area, and so is especially useful for historical purposes-for example, the names of some natural and cultural features have changed over time, and the historical names can be found on many of these topographic maps. The most current map of each area is available from The National Map. As the years passed, the USGS produced new map versions of each area. This mapping was done at different levels of detail, in order to support various land use and other purposes. In 1879, the USGS began to map the Nation's topography. TopoView highlights one of the USGS's most important and useful products, the topographic map. ![]()
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