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it existed, nor glass. Really porphyritic structure is rare, but 

 both augite and plagioclase often appear in an older generation 

 of large individuals ; possibly the rock tried to assume doleritic 

 structure in an intratelluric epoch. The rocks are traversed and 

 coloured in a very variable degree by a red ferric oxide mass. 



It cannot be denied that, though this is true to some 

 extent also of other districts with fine sheeted basalts, it is 

 very curious that a rocky mass of such immense extent, formed, 

 in all probability, during a very long period and during numerous 

 separate eruptive epochs, can show, mineralogically viewed, such 

 great uniformity. Whether this is equally great chemically, is 

 a question that in any case demands closer investigation. 



Strongly divergent rocks are very rarely to be met with. 

 On the other hand, considerable variations in the same basalt- 

 sheet often appear. It can frequently be noticed that the lower 

 part of a well developed sheet is plainly crystalline, while the 

 structure upwards becomes ever compacter and more aphanitic, 

 until the mass finally passes over into amygdaloid or scoria. The 

 upper part of a bank not rarely shows red colouring, and once 

 at least I noticed a bank of this kind pass over at the top into 

 an intensive red, jaspidean, compact rock. 



Worth mentioning are also the minerals which in great 

 variety fill the amygdaloidal spaces. I myself have only observed 

 them in so far as I collected specimens of them wherever they 

 were fine enough to seem suited to a mineralogicai analysis. 

 Nowhere are they so finely developed as in the famous localities 

 on Iceland and the Faroes, but at a few spots really well 

 developed crystals were found, and a mineralogist with plenty 

 of time at his disposal would probably reap a good harvest 

 there. The most important of these places are Henry Land 

 with environs up to Bartholins Glacier^) and С Brewster. The 



') Also called Henry Glacier in Boggilds work. 



