184 ^'^^ Philippine Journal of Science i"* 



downhill over a Kood road from Cayan. The western face of the plateau of 

 Cayan, toward the river, consists of a beautiful hornblende-andesite, which 

 shows on a prand scale spherical segrregations built up in concentric layers 

 or shells. The outer shells are mostly very much decomposed; however, 

 inside one encounters sound cores. 



From Cervantes the road follows the left bank of the river; it was form- 

 erly called Camarin [camino?] del Rio. The valley is very broad here; to 

 the east are the toweriiij; mountains of the cordillera; to the west, extending 

 from north to south, is the costal range, whose profile is very jagged. The 

 creeks that flow from its slopes into the Abra carry much coralline limestone, 

 gravel, and decomposed amygdaloidal rocks. On both sides of the river 

 up to 200 feet above its floor there are thick-bedded gravels, through which 

 the road to Angaqui passes. Angaqui is a Christian village, situated on 

 a knoll of coralline limestone on the left bank of the Abra. From Angaqui 

 we crossed the coastal cordillera through Tovalina Pass at an elevation 

 of about 3,500 feet. One of the most striking peaks of the range at Angaqui 

 is Mount Tila, which because of its needlelike form reminded me very much 

 of the Peter Bott in Mauritius. 



Up to the pass the cordillera consists of a beautiful, partly crystalline, 

 coralline limestone. The innumerable coral fragments are in a very poor 

 state of preservation. 



Very soon, however, after having reached the greatest height, which gives 

 a splendid view of the ocean, on the steep western slope, there appear very 

 thinly stratified, reddish, tuflflike marls dipping south-southwest. They con- 

 tain layers with carbonized plant remains. At Tianagan, the middle point of 

 one of the auxiliary departments of the military district of Lepanto, these 

 tuff-marls are very much folded and faulted. At Cayan I heard that coal 

 had been found at Angaqui, but no one at this place knew anything about 

 the occurrence. It is possible that it lies in a formation similar to the 

 tuff-marl. 



Throughout the country between Tianagan and Lilidda these tuff-marls 

 occur alternating with thick strata of coralline limestone; one reaches the 

 plain at Nueva Cobeta and proceeds to Santa on the seacoast. The coast 

 at this point, several meters above high tide, consists of raised coral reefs 

 which are still in contact with the growing coral. The massive rocks which 

 occur in place in the vicinity are composed of quartz, orthoclase, and chlorite. 



The city of Vigan, the second largest settlement on Luzon, is situated 

 on a sandy, gravelly plain formed by the delta of Abra River. Abra River, 

 as a whole, follows a north to south direction; east of Bangued, the capital 

 of the military district of Abra, however, it turns suddenly to west-south- 

 west, breaks though the coastal range in a narrow chasm at a point called 

 the Bocada, about an hour's journey east of Vigan, and then divides itself 

 into several branches, which rush toward the ocean through shifting 

 channels. The Bocada, to which I made a little excursion, is cut into a 

 complex of clearly stratified rocks, which as a whole show a steep westward 

 inclination. This bedded series is composed of two kinds of rocks, frequently 

 alternating with each other. One is a much crumpled chlorite schist closely 

 traversed with calcite veins; the other rock is coarsely crystalline and is 

 somewhat similar to a protogine gneiss like the rock we have already noted 

 at Santa. For about one-half mile the river courses through this region 

 of crystalline schist in a very narrow bed. At San Quentin the valley 

 broadens, and one enters the district of Abra. 



