Tlie Volcanoes of Griqualancl East. 101 



slightly elongated in a N.W., S.E. direction; a river cuts it in two, 

 but on the northern side the bed of the river runs for a short distance 

 between the encasing Stormberg Beds and the pipe, so that the 

 latter stands up like a cylinder on one bank of the river. The 

 variety of rocks in the pipe is astonishing ; the ground mass is a 

 white sandy substance very like the ordinary trachyte-tuff that 

 occurs with most volcanoes of a type less basic than these particular 

 ones. The percentage of quartz in the ground-mass is unusually 

 high. In this tuft" there are all sorts of varieties of lava : some 

 rounded and vesicular like bombs, others odd-shaped lumps of 

 amygdaloid of every kind of igneous rock that is found in the 

 district, and, in addition, large pieces of sandstone and shales, 

 pieces of rock that have been torn from the sides of the vent and 

 ejected with the other truly volcanic material. The size of the frag- 

 ments lies between minute lapilli to boulders 3 feet in diameter. 

 The beds adjacent to the present surface of the vent consist of 

 Stormberg sandstone, and are bent downwards and inwards towards 

 the pipe, as if the material in falling back into the vent had dragged 

 the surrounding beds with them. There is a good deal of dolerite in 

 the pipe, probably forming a dyke-like mass, but the surface of the 

 ground where the dolerite occurs is too much covered with debris to 

 allow one to make out the relationship of the rock. One very 

 peculiar point about this pipe is that there are a few rare bits of 

 charred wood in the tuff". It seems very curious at first glance to 

 find wood in a volcanic pipe, but one can get a very reasonable 

 explanation if one supposes that before the last outburst there had 

 been a long period of quiescence, and the slopes of the volcano were 

 not only covered with forest, but that trees had actually grown 

 inside the crater. This is by no means an uncommon occurrence in 

 volcanoes at the present day. When then the final eruption took 

 place, some of the trees became dragged down with the rain of falling 

 boulders and ashes, and broken bits of branches became embedded 

 in the tuff. 



This last pipe occurs in the river-bed at the foot of the range, at 

 about 5,000 feet above sea-level. If we climb up the mountain we 

 find a sharp-pointed peak standing out from the general line of 

 escarpment (Fig. 1). It looks peculiar owing to the fact that the 

 dolerite with wdiich it is apparently capped is arranged in rough 

 columns, but on getting on to the peak one finds that the dolerite 

 forms a cylinder surrounded by a rim of white Cave Sandstone ; at 

 one spot there is a well- characterised mass of agglomerate, consisting 

 of a blue, sandy matrix, with numberless rounded bombs of vesicular 

 lava embedded in it. These features are sufficient to establish the 



