116 B. KOTO : THE GEOLOGIC STRUCTURE OF 



runs close by the east shore of the Lake of Bay, and trends 

 south-eastwards. The core of the sierra seems to be of crystal- 

 line schists, which occupy a considerable area to the north-east 

 of Manila, overlaid in part by the Eocene Nummulitic lime- 

 stone, first noticed by v. Richthofen'^^ at Binangonan, on the 

 northern shore of the Laguna de Bay. On the south, the moun- 

 tain resolves itself into at least three parallel chains, as may 

 be conjectured from the outlines of the peninsulas and islands, 

 as well as from the direction of the chief elevations. The western- 

 most ridge consists of Tabayas, Burias and Ticao; the peninsula 

 of Camarines constitutes the middle ; while Caramuan, Batan, 

 and Samar make up the third ridge. The groundwork of the 

 Tabayas peninsula is crystalline schists, overlaid on the north 

 by the tuffite of Majayjay, and on the south by the later Mio- 

 cene or Pliocene coral limestone. 



As regards the geology, the peninsula of Camarines is similar 

 to that of the preceding. Protogene-gneiss and talc- schist are 

 extensively developed in the Malaguit region, with auriferous 

 veins, while the Pliocene limestone makes up the entire west 

 coast. Workable seams of brown coal occur associated with 

 the above limestone. Moreover, Camarines abounds in volcanoes, 

 of which we may mention Tetas, Colasi, Isarog, Iriya which 

 made an eruption in 1628 or 1648, and lastly Albay, all ar- 

 ranged in one series corresponding to the form of the penin- 

 sula, and constituting the Albay or Mayon system of volcanoes. 

 Albay is the type of volcanoes of the Philippines ; it presents a 

 beautiful cone, and is in a state of constant activity. It has 

 made fourteen eruptions since 1716, and on the 26th, July, 



7^)lZeitschr. d. deutsch, geol. ^Gesell, 1862, p. 358. 



