GAZETTEER OF COLORADO. 11 
explored parts of the State, so that in its broader aspects the topographic features 
were pretty well known at the beginning of the American settlements. In 1870 and 
1871 the Fortieth Parallel Survey mapped a strip of country between 40° 30' and 41° 
in latitude and extending across the mountain and plateau portions. Between 1873 
and 1876 the Hayden Survey mapped, on a scale of 4 miles to an inch and with con- 
tour intervals of 200 feet, that part of the State lying west of longitude 104° 30 r , 
including all the mountain and plateau regions. This Survey published a topo- 
graphic and geologic atlas of the State, which in subsequent years had a powerful 
influence in its development. Since the commencement of topographic work by the 
present Geological Survey much detailed work has been done, 34 sheets upon a scale 
of 1 : 125,000 and 18 sheets upon a scale of 1:62,500 having been prepared. The total 
area surveyed is in the neighborhood of 38,000 square miles, or considerably more 
than one-third of the total area. 
There are 14 forest reserves in the State, comprising most of the mountain and 
plateau country. The total area of land thus reserved is 18,236 square miles, or 17 
per cent of the total area. 
