62 ADAMS. 



The southern part of the eastern cordillera is lower and has a 

 peneplaned appearance, and in the region east of the extinct volcano 

 Banahao, which is on the border of the volcanic region, the cordillera 

 is partially covered with tuffs. There are no conspicuous peaks and the 

 higher elevations, in so far as known, fall between 400 and 500 meters. 

 To the south of the geologic map the cordillera continues into Tayabas 

 Peninsula. 



Loboo Mountains. — These mountains lie in an irregular peninsular 

 area on the -south coast of Luzon,' and are bordered on the north by the 

 plains of the southwestern volcanic region. They are distinguished as 

 a separate region because of their discordant trend and the presence in 

 them of diorites and tertiary formations which are not represented in 

 the adjacent southwestern volcanic region. They appear to form two 

 approximately parallel ranges extending in a northeast-southwest (N. 

 60° E.) direction and separated by the valley of the Eosario Eiver. 

 The northwestern range begins in Natoccot Point near which it reaches 

 elevations of about 300 meters. It reaches the altitude 987 meters in 

 its highest peak, and then dies in the plains. The southeast range 

 extends inland from Malabugo Point. Mount Loboo near the coast has 

 an elevation of 946 meters. To the northeast the range lowers to eleva- 

 tions of about 400 meters and then descends to the plains. 



Southwestern volcanic region. — The larger part of this region consists 

 of plains of volcanic tuff sloping toward the sea, Bay Lake, and Manila 

 Bay. Deposits of tuff and volcanic breccias and agglomerates are found 

 on the east border overlying and obscuring the structure of the eastern 

 cordillera. Within the region of the tuff, there are conspicuous moun- 

 tains of eruptive rocks, volcanic peaks, the active volcano Taal, a number 

 of small crater lakes, and some extinct cinder cones. The highest moun- 

 tain is the extinct volcanic cone Banahao, having an elevation of 2,154 

 meters and containing a deep crater which drains to the southwest. The 

 high conical peak Banahao de Lucban is on its northeastern flank and 

 on its southwestern the small peak Masalacot, and some lesser conspicuous 

 hills. Mount San Cristobal lies to the northwest of Banahao and is a 

 high extinct volcanic cone containing three small lakes in its crater. 

 Banahao and San Cristobal are most impressive as seen from Tayabas 

 Bay when approaching Lucena from the west. They can sometimes be 

 seen from Manila, a favorable view point being the Ayala Bridge. Mount 

 Maquiling is next in importance with an elevation of 1,091 meters. It 

 is usually visible from Manila Harbor or the bay front and is conspicuous 

 from the steamers which cross Bay Lake, being situated close to its 

 southern shore. Its summit has several peaks. When seen from Santo 

 Tomas, which lies to the southwest, the peaks define somewhat indistinctly 

 the broken walls of a crater. On the slope of Maquiling there are a 

 number of small solfataras and at its northern base there is an area of 



