G VI1-90 
PHOTOGRAMMETRIC ENGINEERING 
COLORADO PLATEAU 
DATIL SECTION SECTION F 
Fig. 1.11 The Dátil Section. This section is similar to 
the rest of the province, but it is relatively high and has 
many volcanic features. In the background is the 11,000 ft. 
eroded volcanic cone of Escudilla Peak. Its north slopes 
were recently burned off by a disasterous forest fire, the 
scare of which are visible. Surrounding'it is an 8,000 ft. 
pine forested plateau, covered by volcanic cones and capped 
by lava. A lava cap has prevented the erosion of the low 
mesa in the foreground. In the background is the Mogollon 
Rim, which is the province boundary, dividing it from the 
desert country to the south. This is largely national forest 
land, which has had better protection from heavy grazing than 
the lower lands in the foreground, and the difference in veg 
etation cover is visible along the boundary fence. Southeast 
of Sprlngerville, "rizona. October 1949. 
Plate 7.—Many of the characteristics of other sections, especially Sec. E, are present here, 
making it difficult to find distinctive features. 
Map errors are the result of faulty informa 
tion on areas where there is incomplete 
coverage by photography and modern maps. 
In such areas subdivision lines depend upon 
inaccurate base maps, and frequently upon 
the field notes and rough sketches of geol 
ogists and explorers, which often represent 
changes in terrain diagrammatically. Ex 
amples are available where the maps of 
different men who sketched the same fea 
tures show them many miles apart. A 
desert area, which the author recently 
attempted to delineate, was shown on the 
best source maps in locations which varied 
in places by as much as 100 miles. Only 
one photo mission crossed the desert and 
no explorer had ever mapped it in its 
entirety. Physiographic lines in other 
poorly mapped areas commonly err by as 
much as 10 to 20 miles. The photo inter 
preter, especially the inexperienced man, 
who is in greatest need of guidance, 
places his trust in the key and he is 
needlessly misled, or thrown into confusion 
on discovery of these errors. He then loses 
confidence in the entire key. Photo loca 
tions are likewise open to error, though 
less frequently. They depend upon the 
pilot’s trace of his mission, which is subject 
to error under difficult flying conditions. 
If the interpreter is without accurate large 
scale maps for orientation he is forced to 
accept these locations. Again he is led into 
the possibility of a false estimate or into 
disillusionment. 
Another source of error is the use of 
chorographic scales for regional maps to 
delineate terrain changes which can be seen 
in detail only at topographic scales. 
Semple (13) expressed the problem this 
way: 
“Nature abhors fixed boundary lines and 
sudden transitions; all her forces combine 
against them. Everywhere she keeps her bor