GEOLOGICAL RECONNAISSANCE — INP/VJMTA TO TANAY. 487 



Following the Alasasin branch to the southwest a - 1 '' 



narrow limestone belt is first encountered, and this is fol- £ < 1 1 

 lowed by very hard shale or schist beds that strike north- j 

 west and dip 30° to the southwest. Hard shales and 

 graywacke continue for some two miles where another 

 limestone bed, having a strike of IST. 30° W. and a dip of '^^J-'^^' 

 80° to the northeast, crossed. Under the microscope this 

 limestone was found to contain many imperfect fragments 

 of foraminifera, among which were recognized species of 

 Textularia, Pulvinulina and Globigerina. 



x4.t Sungay Creek the trail leaves the valley, ascending 

 a ridge the crest of which has an elevation of ap- 

 proximately 500 meters. As one ascends from the'valley, 

 the sedimentary rocks gradually disappear. The exten- 

 sion of this ridge forms Jalajala Peninsula and the rock 

 which is found here very much resembles that found near 

 Jalajala. It is a light colored igneous rock, composed < ic < 



largely of plagioclase and hornblende and classed as an '"*■ ^ 



andesite, but no well-preserved specimens were obtained 

 for microscopic determination. This ridge is covered 

 with an excellent forest growth as far as the sitio of 

 Balabasa. Between Balabasa and Laguna de Bay the 

 country is open and overgrown with cogon grass in which 

 great numbers of wild deer and hogs exist. -^ 



At the Creek of Elog-na-batjala a tough, hard rock " 

 which looks like a typical basalt was observed; micro- c 



scopically it is seen to be closely related to the andesite. i-o ^ a 



On the crest of the ridge west of Comall Creek a coarse- i » ^ a 



grained olivine basalt was observed, which was distin- = 



guished by large phenocrysts of almost colorless plagio- 

 clase. These were the only good rock exposures to be „ ^ 

 seen on the Laguna de Bay slope, but there is little doubt 5 - 

 that this entire section consists of andesitic and basaltic "° 

 igneous rocks and volcanic tufE. A general geologic sec- 

 tion of the route is shown in fig. 1. a 



A few lumj)s of coal which had been collected and left J 



by Lieutenant Wray a few days before were observed at ° 



the Macadata Eiver. Lieutenant Wray, acting under 

 orders from department headquarters, examined some coal avnvj. 

 beds that were known to occur near the headwaters of the 

 Macadata. They were found to be of doubtful economic J ; 



value, although very little prospecting work was at- o '^ 



tempted. -^ ^ 



No coal outcrops, quartz ledges, or bowlders of mineralized quartz were 

 observed on this journey. 



K 



