7 
■Bfe- ! 
spurs are truncated at 
ill at the left terminates 
jp> from which it slopes 
I tableland that is trav- 
jtlie map each of these 
th its position in the 
9 
distance in feet between 
lie bottom of each map. 
topography of the area 
s small as 1 foot; in a 
as 250 feet. In order 
lly certain contour lines, 
than the others and are 
The heights of many 
o «/ 
units, surfaces of lakes, 
e map in figures, which 
r. More precise figures 
a in the Geological Sur- 
e geodetic coordinates of 
o 
as are also published in 
town in black. Bound- 
city, land grant, town- 
iuous of broken lines of 
•oads suitable for motor 
shown by solid double 
•oads by dashed double 
A survey of Puerto Rico is now 
be published maps is 30,000 * 
The features shown on topographi 
liree groups — (1) water, including 
wamps, and other bodies of wa 
mu n tains, hills, valleys, and other 1 
5) culture (works of man), such a 
pads, and boundaries. The symlx 
matures are shown and explained be 
bme earlier maps, and additional i 
>me special maps. 
All the water features are repres 
reams and canals by single blue li 
v double lines. The larger strea 
ccentuated by blue water lining oj 
t reams- — those whose beds are dry foj 
re shown by lines of blue dots and 
Relief is shown by contour lines 
laps are supplemented by shading 
brown from the northwest across til 
urpose of giving the appearance oi 
le interpretation of the contour lii 
mts an imaginary line on the groil 
f which is at the same altitude a lx 
mid be drawn at any altitude, but 
>urs at certain regular intervals o 
a turn or zero of altitude of the Geolil 
sa level. The 20-foot contour wov 
