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the different sheets with one another. Macroscopicaliy, the 

 following main types can be distinguished: 



1) Compact, aphanitic, dense, black basalts, often showing 

 columnar structure, while spheroidal structure and weathering 

 are to be looked for rather in diabasic forms that are transitions 

 to the next type. 



2) Coarse crystalline, doleritic forms. 



3) Porphyrites, which however seem to play only a small 

 part among the sheet-like basalts. 



4) Red basalts, coloured by iron ochre, often of slaggy 

 structure. 



5) True amygdaloids, perhaps the commonest form of all, 

 very varied in appearance. 



To give a more exact account of any of these vertical 

 sections would scarcely be of interest. However, the rock at 

 C. Brewster is remarkable. It looks, as if we had here two 

 main divisions in the basalt series. The lower consists mostly 

 of a rather dense, even grained, somewhat yellowish grey mass, 

 with indistinct amygdaloidal structure. Above it lies a real tufa, 

 with black scoriae in a yellow vitreous mass. Above this, at the 

 point of contact with the upper division, there is a grey, dense 

 basalt, a red burnt amygdaloid, and an intensively red, sandstone- 

 like rock. Whether it is to this middle zone that we can also 

 assign the numerous fragments of foreign, presumably Tertiary, 

 sandstone, metamorphosed by contact, and also the different-sized 

 pieces of petrified wood-trunks, which characterize this locality, 

 is not certain, but seems to me probable. 



On this follows a huge upper zone, which at the line of 

 contact and in its lower part is made up of a dense, greyish 

 yellow rock. Further W. this zone sinks more and more, until 

 finally it reaches down to the shore. The rock here is a fine, 

 thoroughly crystalline, normal basalt, without prominent surface 

 structures. 



To whîit extent the sequence of rocks observed here is a 



I 



