Example of north arrows on a historical USGS topographic map. Skip to main content. Search Search. Mapping, Remote Sensing, and Geospatial Data. Apply Filter. How do I find, download, or order topographic maps? The best known USGS maps are the ,scale topographic maps, also known as 7. Download all dates and scales of USGS topographic maps free of charge from the following applications or order paper copies of all TopoView - Click on any of the round map scale indicators on the right side of the map.
The National Map Viewer - Click on the What is a topographic map? The distinctive characteristic of a topographic map is the use of elevation contour lines to show the shape of the Earth's surface. 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.
Contours make it possible to show the What is the State Plane Coordinate System? Can GPS provide coordinates in these values? The State Plane Coordinate System SPCS , which is only used in the United States, is a plane coordinate system north-south and east-west lines are perpendicular in which each individual state has between one to six zones, depending on the state's size and shape.
The UTM Universal Transverse Mercator coordinate system divides the world into sixty north-south zones, each 6 degrees of longitude wide. UTM zones are numbered consecutively beginning with Zone 1, which includes the westernmost point of Alaska, and progress eastward to Zone 19, which includes Maine. Are USGS topographic maps copyrighted?
All topographic maps produced by the U. Geological Survey USGS are in the public domain and are not copyrighted except for the following three cases that apply only to US Topo maps produced present : Most maps in the period contain commercially licensed road data see note below. Orthoimages in Alaska are commercially licensed Can I still get the older topographic maps?
Topographic maps originally published as paper documents between have been scanned and published as the USGS Historical Topographic Map Collection. What is declination? At most places on the Earth's surface, the compass doesn't point exactly toward geographic north. A compass needle will always point towards the Magnetic north pole. The pole may not be the exact point since the compass aligns itself to the local geomagnetic field which varies constantly.
The pole is the wandering point in the Northern Hemisphere where the magnetic field points vertically downwards. If a magnetic compass needle is suspended horizontally on an axis it will point straight downwards.
The specific point where this occurs is the Geomagnetic North pole. The Position of the North Magnetic pole moves continually northwestward due to adjustments in the magnetic field in the core of the Earth. In , the magnetic north was still in Canada within the Arctic Territorial region but was in motion towards Russia at a speed of 55 to 60 kilometers per annum.
The three norths are important to map readers and navigators in making them understand topography. The difference between the magnetic north and the true north is the angle of inclination on a horizontal plane mostly referred to as magnetic variation or declination. Each region has a unique declination and it should be accounted for when reading and analyzing a map.
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