23 -5 Dicker son: Baguio Plateau 449 



SUMMARY 



Baguio Plateau is a remnant of an early old-age surface, 

 formed during a portion of Pleistocene time, uplifted to the 

 present elevation of 1,200 to 1,500 meters, and largely eroded 

 during Recent time (Plate 12, fig. 2). Various northern ex- 

 tensions of this peneplain have been recognized at Mount Data 

 and intervening points by Dr. Warren D. Smith. Botanical 

 evidence indicates that in the northern half of Luzon distant 

 mountains with elevations of from 1,050 to 1,500 meters or 

 more were present, and upon these elevations the ancestral 

 stock of the present upland temperate flora was preserved. 

 The vast acceleration of geologic processes in the Tropics is not 

 due to mere quantity of rainfall, but to rainfall delivered as 

 torrential downpours. The irresistible energy of the streams 

 carrying these great volumes of water quickly leveled the moun- 

 tains of early Pleistocene time over much of the area of the 

 northern half of Luzon and reduced them to gently rolling hills 

 and intervening wide shallow valleys. In late Pleistocene time 

 this surface was uplifted in at least two and probably three 

 stages, as the Amsalsal Plateau and the two terraces encircling 

 Trinidad Valley indicate. Accompanying this uplift, faulting 

 upon a great scale upthrust such masses as Mount Santo Tomas 

 and the high mountain in northern Luzon, Mount Data. 



Baguio Plateau cuts across rocks of various ages, diorites 

 of the basement complex, Vigo-Miocene sandstones, Malumbang 

 limestones, and the tuffs and agglomerates of the Baguio for- 

 mation (Plate 12, fig. 3). This plateau is now in a geologic 

 sense rapidly disappearing, through a process of rapid erosion 

 aided by solution of underlying limestone and slides upon the 

 plateau edge due largely to this sapping action, and owing to 

 these agencies our descendants of a few thousand years hence 

 will not enjoy this charming fairy-land. 



