Park. — On the Discovery of Perino-carboniferous Bocks. 449 



succession and relationship of the different rocks are seen 

 to great advantage. 



At the foot of the mountains the dip of the rocks is very- 

 high, but ascending the Awahokomo it gradually decreases, 

 and at the foot of Mount Mary is as low as 35°. Ascending 

 Mount Mary the dip gradually increases, and at the fossilifer- 

 ous outcrop is about 60"^. 



The total thickness of strata exposed in this section is not 

 less than 10,000 ft. The lowest rocks are pale-grey and blue 

 phyllites, generally much crushed and often drossy. The 

 phyllites are followed by thin-bedded quartzite and altered 

 claystone and a great thickness of pale-green altered grey- 

 wacke and breccia, the former occurring sometimes in thin 

 and somer.imes in thick bands, and frequently seamed with 

 a network of small quartz veins. 



Above the upper forks of the Awahokomo blue silky slates 

 are interlaminated with thin layers of quartz, which vary 

 from a mere thread to 4 in. thick. 



Above an altitude of 3,000 ft. altered argillaceous rocks 

 become less abundant. At 3,200 ft. there is a consider- 

 able development of thin-banded siliceous sandstone, almost 

 quartzite, and dark-blue claystone, occurring in thin laminae 

 varying from 1 in. to 2 in. thick. 



From this onward to the summit of Mount Mary the 

 bands of sandstone, greywacke, and breccia become more 

 massive and less altered, and here we meet a few narrow 

 bands of red and green slaty shale which are often streaked 

 with jasperoid segregations. The pale-green aphanitic sand- 

 stones and greywacke, which are so prominent in the lower 

 part of the succession, are now absent. The sandstone bands 

 are coarse and gritty, but the argillaceous beds, lying between 

 two bands of sandstone or greywacke, are still considerably 

 altered. 



The rocks just described are highly altered and schistose 

 near the bottom of the series, and become gradually less and 

 less altered in passing upward towards the top of the 

 sequence. This is partly, but not altogether, explained by the 

 circumstance that the more easily altered argillaceous strata 

 predominate in the lower part, and the more siliceous and 

 consequently less easily altered rocks in the middle and 

 upper parts. 



The rocks in the immediate neighbourhood of the main 

 fossiliferous outcrop are as follows in ascending order : — 



(a.) Grey indurated sandstones, often coarse and gritty. 

 (6.) Blue fissile slates, like slates at Otepopo. 

 (c.) Slaty and flaggy claystones slightly micaceous, con- 

 29— Trans. 



