LANDSLIPS 537 



know that we locate our highways in the tropics in beautiful canyons only 

 at our peril. The change of location of this one road will affect the whole 

 countryside, the growth of cities as well as many minor enterprises. For 

 oiir Philippine highways of the future, in highland country at least, we 

 must resort to the ridges, for on them we are safe, while in the canyons 

 we have overhanging cliffs and powerful undercutting streams to contend 

 with. 



Landslips 



In consequence of the nature of the formations, heavy rainfall, and 

 seismic disturbances, nearly all parts of the archipelago are subject to 

 landslips of greater or less magnitude. This is particularly true of the 

 highlands of Luzon, where in many localities the formations are to a con- 

 siderable extent limestone covered with volcanic flows and loose ejecta. 

 At one place near Sagada, Lepanto subprovince, the writer saw a piece of 

 terrane on which was located an entire Igorot village of several hundred 

 houses creeping slowly down the mountain side. At Baguio, in the case 

 of another slide, he recorded by actual measurement a slip of an inch an 

 hour. This great slide occurred just below the Government hospital, 

 causing some of the adjacent buildings to be moved, and extended in a 

 great semicircle with an arc of between half and three-quarters of a mile. 

 At the time this visit was made the total settling had amounted to over 

 30 feet. A landslide from one side of the Bued River canyon during an 

 unprecedented downpour caused a dam of loose material in the gorge 

 below to a height of 60 feet. When the impounded water broke through 

 this dam everything in the canyon below was obliterated for several miles, 

 steel girders of bridges being carried far out onto the Central Plain below, 

 miles to the south. 



Location and Growth of Cities 



Manila. — The location of Manila is unique not only in the archipelago, 

 but also it is one of the best situated metropolises in the world from geo- 

 graphical, physiographical, and commercial standpoints. In its imme- 

 diate surroundings the following points of paramount importance are to 

 be noted : It is located about half way between the extreme northern and 

 southern ends of the great island of Luzon, almost at the geographical 

 center. It is at the head of one of the best protected bays in the world. 

 It is at the lower end of the largest of the intermontane areas of the 

 archipelago, the great Central Plain of Luzon. It is at the mouth of the 

 Pasig River, the main artery leading to the rich lake country of the prov- 

 inces to the southeast. The narrow opening and wide flaring out of the 

 bay on the inside precludes any possibility of serious damage from seismic 



