222 The Philippine Journal of Science isn 



character of the rainfall, certain plants being grown more ex- 

 tensively where there is a distinct dry season and others where 

 the rain is more evenly distributed throughout the year. A more 

 intensive study of the soils of Luzon has been published by Cox 

 and Argiielles. 3 



Brown and Matthews * have shown that in the Philippines the 

 present distribution of forest and grassland is due to the activity 

 of man combined with climatic influences. Grasslands only occur 

 where the forests have been removed. They are produced and 

 maintained by frequent fires and so are most extensive where 

 there is a pronounced dry season. 



MOUNT MAQUILING 



Mount Maquiling is an isolated volcanic cone, situated on 

 Luzon, midway between the eastern and western coasts, about 

 64 kilometers southeast of Manila, in latitude 14° 10' east of 

 Greenwich. It reaches an altitude of approximately 1,100 me- 

 ters. The geology of the mountain, particularly of the lower 

 slopes, has been described in considerable detail by Abella. s 



The main crater of the volcano has apparently been extinct 

 for a long period. The rim has been eroded until it has become 

 a series of peaks which, except on very steep slopes, are covered 

 with deep soil. Volcanic activity has, however, not entirely 

 ceased, as numerous fumeroles and hot springs occur around 

 the base and on the lower slopes. 



On the eastern and southeastern sides the mountain grades into 

 the surrounding plain at an elevation of approximately 50 meters. 

 On the lower slopes there are layers of soft volcanic tuff. At 

 elevations of from 50 to 100 meters these layers of tuff, which 

 are mixed with layers of soil, may be many feet thick and are 

 frequently near the surface. The layers near the surface are, 

 however, usually thin, soft, and very much broken. Such a 

 layer, about 30 centimeters thick, is frequently found about 30 

 centimeters below the surface, and traces of such a layer occur at 

 elevations as great as 300 meters or more. West and Cox 6 give 



* Cox, A. J., and Argiielles, A. S., The soils of the Island of Luzon, 

 ibid., Sec. A (1914), 9, 1-50. 



* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests, 

 ibid., .Sec. A (1914), 9, 413-561, Pis. I-XIII. 



1 Abella y Casariego, D. E., El Monte Maquilin (Filipinas) y sus ac- 

 tuates unanaciones volcanicas. Iraprenta y Fundacion de M. Tullo, Madrid 

 (1885), 1-28, Pis. 1-2. 



* West, A. P., and Cox, A. J., Burning tests of Philippine Portland 

 cement raw materials, This Journal, Sec. A (1914), 9, 79. 



