4Z% SMITH AND .EDDINGFIELD. ' ;\ \ 



of basalt cvi through this roch (diorite), but'tkey a^-e ainiinportant^ exi 

 cepting that the directions of the dikes seem to be quite uniformli/ along 

 east and west lines. In^ common with the system vf ore deposits in'ihe 

 dioiite (andesite) the majority of the veins striking east and west j, or 

 approximately in that direction, this prevailing, direction would point 

 to a line, or rather a direction, of tueakness in the main mass of the 

 rock." A great many of the veins in the district, I mean the important 

 veins, do not strike in an east and west direction, but in a large number 

 of cases northwest and southeast. 



The principal intrusion of the district is the large mass of quartz 

 diorite already referred to, in the lower part of the Antamok Valley. 

 Here it forms one wall of the Camote ore-body and cuts it off sharply, 

 so that the vein is not found on the western side of the river. The many 

 small basalt dikes do not appear to bear any relation to the veins. 



SEDIMENTARIES. 



The Major Creek formation. — We have already referred to some 

 sediments which are to be found occurring beneath the later andesite 

 of Major Creek. The exposures are not extensive, nor are they trace- 

 able for any great distance. They consist of shales, sandstone, and con- 

 glomerate, but no limestone was found. The thickness is not great, 

 apparently not over 100 or 200 meters. 



The conglomerate has an oxidized, sandy matrix and pebbles derived 

 from the andesite beneath. It is fossiliferous. The fossils are of com- 

 paratively recent forms. We correlate this formation with the con- 

 glomerate in the Trinidad Water-gap. 



The sandstone is best shown in the gulch just below Mansion House. 

 Here it is yellowish-white, and extremely hard, the sand grains having 

 been recemented by the silicious waters wliich poured oiit at many points 

 in this region at a later period. These will be referred to later. 



The shale, which is gray in color, is best seen at the entrance to tlie 

 Engineer tunnel on the Major Mines property. It is somewhat brec- 

 ciated and in places it also has been lecemented by silicious waters. Eed 

 ferruginous- shale also has been seen in this locality. 



The absence of the limestone here is accounted for by erosion, and 

 the comparative thinness of these formations at this point by the fact 

 that the old shore line was approximately in this place. These same 

 sediments outcrop again in the Benguet Eoad, and on either side of 

 the Santo Tomas Trail. Eveland, in discussing the western portion 

 of the District, has already pointed out the occurrence and characteristics 

 of these sediments. 



The Baguio formation. — We have given the name of the Baguio for- 

 mation to all the more or less silicified and metamorphosed deposits, 

 which cap the highest hills around Baguio, particularly in the vicinity 

 of Government Center and Camp John Hay. In places the formation 



