214 



The Philippine Journal of Science 



1915 



•5 



coming in on both sides or joining the main stream along lines 

 corresponding to the strike of the formation. For some distances 

 the main streams themselves follow the strike, but as a rule 

 they cut nearly at right angles to it. The geologic structure is 

 reflected in the topographic aspect of the country and is charac- 

 teristic of block mountains. As we look upstream from the lower 



courses, we see long gentle slopes; 

 but when we ascend and look back- 

 ward, we are confronted by abrupt 

 slopes due to the upturned edges 

 of the formation. The conditions 

 may be represented by the diagram 

 as seen in fig. 1. 



Where the rocks are hard, the 

 streams cut through in narrow 

 gorges, but where the formations 

 are soft, as in the shales and some 

 of the soft limestone, the country 

 is open and the streams run in wide 

 valleys. There are many places in 

 Panay where one encounters box 

 canons, which at the time of high 

 water are very difficult to pass 

 through. These are usually in 

 the hard resistant conglomerate. 

 Many of these would afford excel- 

 lent dam sites. Where the streams 

 have cut back into the harder rock, 

 such as volcanic agglomerates and 

 diorite, there is no system to their 

 course. They seem to follow no 

 particular lines, save possibly here 

 and there the jointing has exerted 

 a local influence. When the low 

 country is reached, the streams 

 take their own courses again and meander irregularly over the 

 broad plains. 



DISTRIBUTION OF THE PEOPLE 



a. 

 a 

 u 

 te 

 o 



a 

 o 



fa 



In the report of the Philippine Census of 1903 there is a general 

 map showing the distribution of the various tribes of the Islands, 

 and the map of Panay, as shown in fig. 2, is reproduced from 

 this. Following the cordillera and the tongue of highland, cut- 



