346 Geology of 



rounded by attrition during their ascent from the volcanic vent and 

 before they had found a final resting place, or they might have been 

 rolled in a water-course descending from near the summit of a volcanic 

 cone, of which at present the remains are only to be found in Mount 

 Sinclair, which in that case would be of greater age than the Mount 

 Herbert system. Theprincipallava-streamswhichissuedfrom this volcano, 

 and have been preserved, run in a northerly direction into Lyttelton 

 caldera, and can be followed from the summit of Mount Herbert to 

 the sea. They form that remarkable assemblage of streams bounded 

 on one side by Ehodes' Bay and on the other by Charteris Bay, and it 

 is in following them from Diamond Harbour that the summit of 

 Mount Herbert — where the most extensive panoramic view of this 

 part of ^N~ew Zealand can be obtained — is reached with the least 

 difficulty. The remnants of several craters on and near the summit 

 of Mount Herbert, of which about one-half of the rim in each case 

 has been preserved, can easily be seen ; the principal ones are open 

 towards Lyttelton Harbour and the Kaituna valley. 



The other system, of which the remaining caldera wall rises in 

 Mount Sinclair to 2S00 feet, intersects both the Little Eiver and 

 Akaroa calderas. Its barranco at the entrance to Pigeon Bay leads 

 into the sea. It consists of rocks similar to those described as forming 

 the Mount Herbert system, and its relations to the latter are rather 

 obscure and complicated, as the lava-streams of both mix with each 

 other, and owing to dense forest, generally clothing the slopes, no 

 clear sections can be obtained to settle several important points in 

 connection with them. It is an important fact, that the formation of 

 dykes ceased after the older caldera walls of Banks' Peninsula had 

 received their present form, and before the Mount Herbert and Mount 

 Sinclairs ystems had been built up. All the lava-streams belonging to 

 these two systems, even on their very summits, have never been fissured 

 in any way, so as to prove that the volcanic energy by which the dykes 

 were formed had already spent itself, or at least, if still existing, could 

 not reach so high as to bring its effects under our observation. 



To facilitate their task to those of my readers who have an oppor- 

 tunity of examining the remains of both volcanic systems now forming 

 Lyttelton Harbour, I shall here offer the necessary data to distinguish 

 between them. The older caldera wall beginning on the northern side 

 of Gebbie's Pass rises soon to a considerable altitude, forming seven 

 prominent peaks, as far as Dyer's Pass (957 feet). They are called 



