302 Geology of 



In Germany, rocks of this character are named hyperites, but I have 

 no doubt that the analysis of the Kew Zealand rocks will show- 

 that this resemblance is only apparent. ]S"o doubt the peculiar 

 conditions under which these rocks made their appearance 

 may account for their structure. They were, doubtless, deposited 

 in shallow water, or even some of the beds might be of sub- 

 aerial origin. Two forms of texture are easily identified, both 

 occurring in the dykes and the coulees or streams. One of them 

 more compact, although still haying a doleritic and sometimes a 

 porphyrinic texture, with small grains or imperfect crystals of felspar 

 interspersed. Another more granular and amygdaloidal, the pores 

 and cavities either lined with sphaerosiderite or filled with chalcedonic 

 quartz. Some of the streams are of considerable dimensions, Mr. 

 M. B. Hart having passed through one which has a thickness of about 

 75 feet. There are two localities where dykes belonging to another 

 series occur, having been erupted during the formation of the greensanda 

 above the saurian beds. These dykes have quite a basaltic texture. 

 Their being of deep-seated submarine origin may account for this 

 difference in texture. In any case we have to classify them with the 

 next series — the true doleritic rocks of which many have a porphyritic 

 or even granitoid texture. They have been erupted after the formation 

 of the coal-bearing beds, often dislocating and altering them in a most 

 remarkable manner, and having preserved portions of these formerly 

 more extensive strata from entire destruction. 



The igneous rocks on the western side are different in texture, and 

 resemble some of those varieties of basic rocks on the continent of 

 Europe, to which the term melaphyre has been applied, but they are 

 also different from the basic rocks underlying the quartziferous 

 porphyries on the eastern flanks of the Alps. The basic rocks, north 

 of the mouth of the Paringa, occur in different textures, of which a 

 porphyritic melaphyre is the most conspicuous. It has a compact 

 black matrix, containing a large number of hornblende crystals, and 

 grains of magnetic iron. The hornblende crystals enclose sometimes 

 very small grains of a yellowish green mineral, possibly olivine. The 

 melaphyres at Arnott's point have also a compact black matrix, some- 

 times with a blueish tinge, enclosing small crystals of felspar 

 (labradorite ?), and hornblende ; the joints are filled with carbonate of 

 lime. The rock breaks in such small polyhedric pieces, that it is 

 almost impossible to secure a properly sized specimen for the cabinet. 

 It forms here coulees of 15 to 30 feet in thickness, alternating with 



