A THEORY ON THE FORMATION OF THE CENTRAL 

 LUZON PLAIN. 



By Raf. Heeesiann. 

 (Manila, P. I.) 



Professor Suess, in his work, "The Face of the Earth," compares the 

 Philippines to an open fan. The handle is formed by northern Luzon 

 and the ribs widen out toward the south. There are several lines of 

 ranges distinctl}' marked b}' islands. The most western starts from 

 North Borneo and reaches through Palawan, the western point of Min- 

 doro, and the Province of Zambales on Luzon; next follows a line along 

 which is an-anged eastern Borneo, the Sulu Archipelago, Avestern Min- 

 danao, Negros, and Masbate; then central Mindanao, Leyte, and Mas- 

 bate; the fourth strikes from eastern Mindanao, Samar, and southern 

 Luzon to the central Luzon ranges ; and the last can be traced from Catan- 

 duanes, Camarines, and Polillo, to the east coast of northern Luzon. 



The formation is very similar to the Alpine system in Europe, where 

 we have the parallel to northern Luzon in the western part. The first 

 chain to separate is that of the Appenines through Italy, then follow the 

 Dinaric chains through Turkey, farther north two small ranges, the Ivans 

 Cica and the Hungarian Mountains, and the last ones are the Carpa- 

 thian Mountains. At the separation of the Alpine ranges is the Vienna 

 basin, a nearly circular sunken piece of ground, which in the Philippine 

 Islands is represented on a much larger scale by the Sulu Sea with the 

 following boundaries : To the westward, Palawan ; to the southward, Bor- 

 neo, and the Sulu Archipelago ; to the eastward, Mindanao and Panay ; to 

 the northward, Mindoro. 



All the afore-mentioned ranges spread out toward the south, approach 

 each other toward the north, and form a solid moiintain massif from east 

 to west in northern Luzon, interrupted only by the long erosion valley of 

 the Cagayan Eiver. It appears all tlie more strange to me from a geologi- 

 cal point of view in that at the Gulf of Lingayen these mountains suddenly 

 break off and we find the central Luzon plain between the mountains of 

 Zambales to the westward and the central ranges to the eastward. It 

 attracts my attention still more, because the Island of Mindoro lies in 

 front of the central plain to the soiithward like a barrier. If this were 



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