80 ADAMS. 



the northeast of that town, is best referred to the barrio of San Guillerma, 

 which is situated on the east side of the valley of the Morong River, 

 opposite Richthofen's localitj', which is on the west side of the valley. As 

 seen from San Guillermo the limestone forms a high bluff with a peak 

 rising to an elevation of about 100 meters above the wide, cultivated . 

 river valley. , To the south of the peak the limestone at a much lower 

 elevation disappears under a basaltic agglomerate. The matrix of this 

 agglomerate is tufaceous and incloses fragments and even large blocks 

 of cellular basalt. This agglomerate partially overlies the limestone on 

 the west. The eastern slope of the limestone ridge is that of a valley 

 slope with a talus of limestone. 



The limestone bluff extends northward to the vicinity of Teresa, but 

 there it is not so massive. To the north of Teresa between two branches 

 of the stream valley there is a ragged hill consisting of massive limestone. 

 Following the trail from Teresa to Antipolo, limestone bowlders and 

 outcrops are seen along- the border of the valley and them in ascend- 

 ing the hill argillaceous limestone strata and some beds which are 

 even arenaceous are obsejved, but these exposures are very limited, the 

 country being covered with cogon grass. The limestone in the hill 

 between Antipolo and Bosoboso is the most conspicuous outcrop in that 

 vicinity, but it continues to the north and south in the ravines and on 

 the hill slopes. In traveling to it from Antipolo one finds outcrops of 

 a thinner, bedded limestone in descending from the upland on which 

 Antipolo is situated, so there is evidence of a zone in which this 

 formation occurs. 



Eeturning to the consideration of the "fine-grained hornblendic 

 slates" which Meyer saw lying on the limestones and the "compact 

 breccia composed of limestone and diabase-aphanite" which Von Drasche 

 observed clipping to the east on both sides of the limestone at Poray 

 Creek and containing certain beds which he called diabase tuff, it is 

 proposed .to explain their characters by giving the succession at the 

 locality of the gorge. Approaching the gorge from along the road from 

 Montalbon, in the cuts in the foothills on the south side of the river 

 there are exposures of basalt which has been sheared and jointed by 

 dynamic action and are considerably altered. The next exposures in. the 

 north bank of the river bed are variable, stratified, clastic beds which dip 

 to the eastward. Succeeding these beds is a heavy limestone showing 

 in a hill on the north side of the river and found at the roadside south 

 of the stream. It is followed by stratified deposits which are sandstones, 

 tufaceous beds, fine-grained, hard shales exhibiting color banding, fine 

 and coarse conglomerates containing in places limestone pebbles, and 

 some brecciated beds. These exposures are in the bed and bank of the 

 river and in the bed of a small tributary from the south. The dips are 

 to the eastward and are steep. Succeeding the variable series just 



