GEOGRAPHY'S CONTRIBUTION 211 
such studies have been properly eftected. There is no substitute, 
for instance, for a detailed survey of proposed storage basins, but 
the student of landforms who interprets most of the sert@o as a 
resurrected fossil plain, a worn-down, old-age surface, can predict 
that the terrain, broadly open and unobstructed, is not likely to 
provide much depth in proportion to the free water surface of the 
reservoir. In short, the geographical approach will indicate that 
there is little justification for the belief that construction of such 
Figure 7. Suggested explanation for the watergaps carved through 
the Serra de Santa Catarina, Paraiba State, by Piancé River and its 
tributary, the Aguiar. Sequence of strata in the sedimentary cover is 
assumed analogous to that exposed in the residual Araripe tableland, 
some 125 kilometers to west. Following superposition on the under- 
mass, drainage shows tendency to adjust to structure. 
