Geology 



for a start at daybreak, and sailed down the river to the 

 spot where we had previously landed. Here we found 

 that the banks had been carried away by the flood 

 waters, owing to the heavy rains, and that the country 

 was under water for a considerable distance from the 

 river. It was, therefore, necessary to find another land- 

 ing place, and, in consequence, we again headed up 

 stream and landed a few miles south of the Permian 

 outcrop, where the flood-plain was narrow and had not 

 yet been submerged. 



On landing we saw in front of us a steep-sided hill 



FIG. 28. Section of Basalt Mountain. <s, Permian Limestone ; , Triassic 

 Sandstone ; c, Triassic Marl ; d, Basalt of Volcanic Neck. 



with a rounded top quite unlike any of those in its 

 neighbourhood, and decided to investigate its structure. 

 It was found to consist, so far as its lower slopes were 

 concerned, of Keuper Sandstone, but its summit was of 

 a hard compact basalt. From an examination of a 

 section exposed in the banks of a small stream which 

 flowed down the side of the hill, we concluded that this 

 was a volcanic neck, the conduit of an ancient volcano 

 which had become finally plugged by the solidification 

 of the lava which filled it (Fig. 28). 



The compact texture and durable nature of the 

 basalt convinced us that it would make excellent road 



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