National Cartographic Information Center (Continued) 
Map Scale 
1:2,500,000 
1:500,000 
1:250,000 
1:100,000 
1:63,360 
(Alaska) 
1:62,500 
1:24,000 
1:20,000 
(Puerto Rico) 
Type of Information 
Very general distribution 
of limited number of very 
large and heterogeneous 
rock units. 
General distribution of a 
larger number of somewhat 
heterogeneous rock units. 
Little information on 
depth. 
Semidetailed distribution 
of large numbers of 
fairly homogeneous rock 
units. Some information 
on depth. Often has 
topographic base. 
Detailed distribution of 
large number of homo- 
geneous rock and surfi- 
cial units and consid- 
erable information on 
thickness and depth. 
Generally has topo- 
graphic base. 
Very detailed distribution 
of large number of quite 
homogeneous rock units. 
Surficial deposits may 
be shown on separate map. 
Much information on 
thickness and vertical 
extent of rock units. 
Has topographic base. 
VIII-5 
Purpose 
General planning and 
resource evaluation 
over very large 
regions (Federal 
regions, very large 
states). 
General planning and 
resource evaluation 
over large regions 
(large states, 
river basins). 
Common scale for 
older state maps. 
More detailed plan- 
ning and resource 
evaluation in 
medium-sized areas 
(small states, 
large counties, 
national forests, 
mineralized belts). 
Detailed planning, 
land-management, 
and resource 
studies (mining 
districts, urban 
areas, many 
counties). 
Detailed planning, 
site selection, 
resource evalua- 
tion, and explora- 
tion (cities and 
towns, subdivi- 
sions, mining 
districts, mine 
sites, large con- 
struction 
projects). 
