Volcanoes and Seismic Centers of the Philippine Archipelago, Volume 3

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Department of Commerce and Labor, Bureau of the Census, 1904 - Earthquakes - 80 pages
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Page 18 - Mainit in Pantabangan, of Sibul in San Miguel de Mayumo, and of Sibul in Norzagaray, occur in a right line running north and south, approximately parallel to the direction of the cordillera and to that followed by the outcropping of the beds of conglomerates, sandstones, slates, and limestones which constitute the said post-Tertiary formation of the center of Luzon.
Page 19 - Philippines is something as follows: From early Paleozoic times onward an archipelago has usually marked the position of these islands. Prior to the Eocene nothing definite is known of them, but further investigation will very likely disclose Paleozoic and Mesozoic strata there, as in the Sunda and the Banda islands. During the Eocene it is probable that the lignitic...
Page 9 - Zone, between 4° 4' and 20° 3' north latitude and 116° 4' and 126° 34' east longitude from the meridian of Greenwich. It is surrounded on the north and west by the China Sea, on the east by the Pacific Ocean, and on the south by the Sea of Celebes.
Page 19 - After the Cebuan lignitic epoch a great uplift and folding took place, and this may have been a detail of the late Eocene movement which so profoundly modified Asia and Europe. It must have brought about temporary continuity of land area between Borneo and Luzon. Somewhere about the middle of the Miocene the country sank to a low level. Many of the present islands must then have been far below water, while Luzon and Mindanao were represented by groups of islets. Observations appear to suggest that...
Page 19 - Miocene horizon, and very probably at 9154—01 6 the post-Eocene upheaval. If the semiplastic marls of Cebu are all Miocene, the earlier andesitic rocks, at least, date back nearly to the great upheaval. Among these rocks, also, there is sometimes a tendency for the basalts to follow the andesites, but the one dacite found at Corregidor is later than the andesites of that island. The relation of the trachytes to the andesites is not certain, but the sanidine rock is probably the earlier. A very...
Page 19 - Cebiiwas deposited, and the contorted indurated strata, which in other localities also carry black lignite relatively free from water, should be referred provisionally to this period. Whether the nummulitic limestone found at Binangonan is Eocene seems to me to be an unsolved question. After the Cebuan lignitic epoch a great uplift and folding took place, and this may have been a detail of the late Eocene movement which so profoundly modified Asia and Europe. It must have brought about temporary...
Page 22 - ... radius, and seldom extend over an area with a radius of 100 or 200 miles. The former are very probably the result of sudden accelerations in the process of rock folding, accompanied by faulting and molar displacements of considerable magnitude; whilst the latter are for the most part settlements and adjustments along the lines of their primary fractures. The relationship between these two groups of earthquakes is therefore that of parents and children. The former, which represent a disturbance,...
Page 78 - Balite, and at points above Bayabas, tend to the belief in extensive displacements, faulting and slipping of the entire strata, leaving more or less gradual and regular slopes upon the west and abrupt faces to the east and northeast, certainly not to be ascribed entirely to the effects of erosion. The Angat and Bayabas rivers are two characteristic streams of Bulacan, rising in the cordillera and finding their ways through the foothills.
Page 10 - ... nearly related from a structural point of view. The southwestern ranges seem to gather in toward the eastern edge of the Philippines as do the branches of a tree to its trunk. The eastern coast range of Mindanao is continued southward by the Tulur Islands and others to Gilolo, in the Moluccas.
Page 20 - We may truly say, speaking of the Philippine archipelago, what Mr. AR Wallace says of the Malay archipelago: In the whole region occupied by this vast line of volcanoes, and for a considerable breadth on each side of it, earthquakes are of continual occurrence, slight shocks being felt at intervals of every few days or weeks; while more severe ones, shaking down whole villages and doing more or less injury to life and property, are sure to happen in one part or another of this archipelago almost...

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