AREA AND CoNFIGCRATIoN. The area of Luzon has been variously estimated at from 37,000 to 47,000 square miles. The olGeial estimate of 1902 is probably the most nearly correct, and gives 43,075 squae miles for the mainland amid 1160 for tlme 311 small dependent islmnuls, giving a total of 44,235 square miles, which is nearly the total for the State of Pennsylvania. Its area is according to this estimate somewhat less than that of Mindanao (q.v.). Time shape of the is land is extremely irregular. It may be divided into tlu•ce parts, connected by narrow isthnnises; Northern Luzon, the main body, with n length from north to south of 270 miles amid a width of 130 to 140 miles; Central Luzon, 56 by 90 miles. connected with the first by two istlmniuses, one on each side of the Laguna de Bay; :umd Smrtheru Lunoim, a long, narrow, and irregular body stretch ing 100 miles to time southeast. The coast is very much indented, «'itlm numerous large bays, some of which form excellent. harbors. The chief bays are, on the west coast, time Gulf of Lin gayibm and Manila Bay; on the south coast, the bays of Tayabas and Jiagay. and the port of Sorsogbu; and on the east coast, the bays of Albay, Lagonoy. San Miguel, and Laubn.
The principal dependent islands belonging to Lurou arc, with their areas in square miles, the liataucs (Si) and the Bahuycrmcs (179), two groups of small islands lying north of Luzon. the former being the extreme northern group of the archipelago: Polihlo Island (203), near the eentro of the ('astern ('mast: Alabat (60), at the mouthm of the Bay of Lambe; C'itanduames (704), oil' the southeast coast : and a nnmiiber of smaller groups and islets, chielly off the east coast.
GEoLocr ANn TopooRApilr. Our knowledge of time geological structure of Luzoni is meagre, owing to time natural difficulty arising from the dense vegetation, winch leaves the rocks exposed in very few places. The geological formations, however, inclimde the following: Gneiss and dirt basic rocks, Eocene limestone, conglomerates, sandstones, recent formations containing marine fossils, banks of coral limestone, and recent vol canic rocks. Extensive inland beaches contain ing fossils of existing marine species indicate a recent upheaval, and Southern Luzon was prob ably at no very distant period a separate island.
The mountains of Luzon are included in three principal ranges. which unite in a ennonon nu cleus at 3Iount Caraballo Sur on the northern boundary of the Province of Nueva Eeija in North Luzon. The Sierra Madre range stretches in a continuous chain along the eastern coast, ter minating in Cape Engano, the extreme northeast ern point of the island. The, Central and North Cordilleras run in a more broken chain parallel with the western coast, and with the Sierra Madre inclose the large basin of the Rio Grande de Cagay5n. The third great system runs south ward along the eastern coast and occupies the whole of South Luzon, terminating in Point Surd at the extreme southeastern end. The principal detached chain is the Cordillera de Cabusiltin, running along the western coast from Manila Bay to the Gulf of LingnyOn. inelosing between it and the eastern chain the large central basin of the Agno and Pampanga rivers. The average height of these ranges is from 2000 to 4000 feet, Mount Datd of the Central Cordillera rising to a height of 7364 feet, the highest point in Luzon next to the isolated volcano Mayon, which reaches a height of 7566 feet.
There seem to be two distinct lines of volcanic activity in Luzon, the eastern line containing the active volcanoes of Bulsan, Bacon, and Mayon in the southeastern part. Cana at the northeast ern extremity, and the extinct IsarOg north of the western line contains the active vol cano of Taal in West Central Luzon, and the ex tinct peaks of Arflyat and Stingay. Mayon is the most active, and has in the past century emitted considerable quantities of lava. but all of them seem now to be in the last stages of activity. Earthquakes are of frequent occurrence. and have on several occasions caused great losses of life and property, notably in 1863, when large parts of Manila were laid in ruins, and in 1866, when the whole island was convulsed with a series of severe shocks. The style of architecture has to be adapted to withstand these disturbances.