The Birmingham age-herald., 1911-09-19
MAP
 IS NOW FINISHED
Maps Showing Every Physical Fea- ture of Quadrangle Supplied
 By Uncle Sam

Washington, September 1s-(Speclal.)-- The engraving of the new government topographic map of the Columbana quadrangle has just been completed by the United States geological survey at Washington, and the map is available for distribution. This map represents by far the most complete survey ever made of this section of the state. It shows so clearly every physical feature of the country covered that the character of any part of the quadrangle, as well as the shapes and areas of the hills and valleys, can be seen at glance The elevation of any particular point in the entire area can be easily determined This relief of the country Is graphically shown by reans of brown contour lines each one of which represents a certain elevation above the sea-that is. the traveller fol- lowing the course shown by one Of these contour lines will go neither up hill nor down hill but on a level. The elevation indicated by every fifth line is shown by figures on the map, and it is interesting to determine the heights of different points, by simply counting the contours up or down from one of the marked lines. IT Is easy to understand how such map is of prime value to the engineer who may be laying out railroad or trolley route, highway, drainage or irrigation system-n fact, any piece of engineering work. The water features of shown In blue, with the same exactness of outline as the land features. In addi- tion to the topography, the map shows, in black, all the works of man--roads, principal bridges, towns, houses. etc.
 The topographic mapping done by the geological survey represents the highest type of geogra phic work. and the maps shcw substantially everything as it is on the ground at the time of survey. In making the survey of this particular area the topographers tramped over pracn- cally every portion of the quadr angle, hundreds of miles being thus covered.
 Permanent iron bench marks. showing exact elevations, were also set at varlous points in the quadrangle. The location of these marks is indicated accurately on the map. and they can be used for all time as the basis for any further eleva- tion surveys desired. This sort of map r,akng Is very different undertahing from that of constructing an average eeogra phical map. which Is generally matter of mere approximation and compi- lation. Everything on the geological sur- vey topographic sheet is exact and true to nature.
 This sheet forms but one small section Of the great topographic atlas or map of the United States, which the geological survey is making, and which will be the largest and yet most detailed map in the world. Already nearly 1900 of these sneets have been completed, covering over tl.ird of the country.
 In some parts of the country much of the work is carried through rough and almost impossible areas. with dense for ests, insurmountable precipices, or deep morasses. Hundreds of temporary camps are made during each field season. at al tiiudes ranging from above snow line to below sea level All this work is followed by an enormous amount of office draft ing. and the task is finally completed in