DENVEE OF SOUTII TABLE MOUNTAIN. 163 



At horizons corresponding to this outcrop there are in many places 

 indications pf the presence of similar strata, through small exposures or 

 surfaces strewn with pebbles. 



On following the footpath up the ridge a number of outcrops of sandy 

 strata may be found, though seldom of an extent deserving special mention. 

 The beds shown are often so fine-grained that their composition may not 

 attract attention. At the northern base of ( 'astle Rock the contact of basalt 

 and sandy strata is shown at several points near the path, and other 

 outcrops reveal the character of the adjacent beds very well. 



Ahout 250 yards southeast of ('astle Rock there is a tine outcrop of 

 one of the most persistent beds shown in 'Table Mountain, and one that 

 conveys most readily and clearly an idea of the characteristic composition 

 of the strata of the formation. It is a dark conglomerate, 15 to 20 feet in 

 thickness, which here forms a small cliff at about 20 feet below the basalt 

 sheet. It is chiefly made up of dark andesitic pebbles of many types, 

 varying in diameter from 5 inches downward. The matrix is a coarse 

 sand of eruptive origin, prominent among the particles being augite in 

 isolated prisms with terminations, the edges not having been sufficiently 

 rounded to obliterate the form. The sandy parts of the bed develop in 

 places to wedge shaped masses exhibiting in their relations to each other 

 and to the conglomerate a very marked cross-bedding. Above this 

 conglomerate are dark sandstones continuing upward to the basalt, which 

 are characterized by the abundance of distinct augite crystals. Below are 

 similar sandy strata. 



The variety of andesites represented in the conglomerate is meat, as 

 will be seen by a reference to the petrographical chapter. Most of them 

 are augite-andesites with varying amounts of hornblende and biotite, but 

 no type here found contains hypersthene, while such rocks are common in 

 the higher strata shown in Green Mountain. One variety is very fight 

 colored, aside from the sparsely distributed augite prisms which correspond 

 closely to those mentioned as occurring free in the sandy matrix of the 

 conglomerate, and in the sandstones above. The variation in silica is 

 great, some being very basic, while others contain free silica in the form of 



