X. A, 3 Smith: Geology of Panay 213 



yans, and their number amounted to 775,202 according to the 

 census of 1903. The temperature, rainfall, and vegetation con- 

 ditions of Panay are very much like those of the Island of Cebu. 

 One Cordillera runs almost from north to south separating the 

 Province of Antique from the Provinces of Capiz and Iloilo, This 

 Cordillera lies much nearer to the western coast than to the east- 

 ern and follows a sinuous course starting in the extreme north- 

 west corner of the island, winding eastward, and then swinging 

 back to the southwest corner. In the northeastern part of the 

 island there is a mountainous cluster, but no true cordillera exists. 

 Between these two is considerable flat country, but a little north 

 of the center of the island is a highland tract connecting the 

 western cordillera and the eastern mountains. Owing to the 

 necessary vertical exaggeration in the relief map (Plate I), 

 the true physiography of the central plain does not appear in 

 the photograph. North and south of this divide there is low 

 country. The largest tract of plain country is comprised of 

 what is called the Iloilo plain, the lower part of which is chiefly 

 a delta. The largest streams of the island start on the eastern 

 slope of the cordillera and run east or north of this and then 

 turn to the south and meander across the Iloilo plain. The 

 slopes on the western side of the cordillera are much more 

 precipitous, and the streams there are short and swift. Abella's 

 report gives detailed descriptions of the various mountain passes, 

 the drainage in Panay, and profiles showing the general character 

 of the skyline in various parts of the island. 



PHYSIOGRAPHY 



In Abella's report there is little mention made of the physio- 

 graphic and geologic factors underlying the principal charac- 

 teristics of the country. The relation of topography to geology 

 and the human response to these material factors have been 

 shown in many parts of the world, but very little has been 

 written on this subject in its relation to the Philippine Islands. 

 First, I wish to draw attention to the eflfect of the geology upon 

 the topography. The dominant rocks in Panay — that is, in the 

 habitable portion — are Tertiary sedimentaries — clays, sand- 

 stones, shales, limestones, and conglomerates. We find these 

 lying blanketlike over parts of the Iloilo plain and extending up 

 the sides of the cordillera. In the lower part of the streams 

 rising in the cordillera we find the course of the streams at 

 right angles to the strike of the formation — that is, in the direc- 

 tion of the dip. As we go up these streams, we find tributaries 



