Smith Creek Valley, Nevada - 30x60 Minute USGS Topographic Map blm The official navigation textbook used

The official navigation textbook used in outdoor education courses by thousands of students

Idaho-Wyoming Overthrust Belt

or sitting beside a campfire in Algonquin Provincial Park

and delivering a few surprises along the way

and driest area in North America

Smith Creek Valley, Nevada - 30x60 Minute USGS Topographic Map blm The official navigation textbook usedThe distinctive characteristic of a topographic map is that the shape of the Earth's surface is shown by contour lines. Contours are imaginary lines that join points of equal elevation on the surface of the land above or below a reference surface, such as mean sea level. Contours make it possible to measure the height of mountains, depths of the ocean bottom, and steepness of slopes. A topographic map shows more than contours. The map also includes