Haast. — Researches in Sumner Moa Cave. ' 55 



cave and of the surrounding country, as in the summing up it will be necessary 

 for me to refer to them in elucidation of some of the points at issue. 



Geological Features. 

 Banks Peninsular, an extinct volcanic system of large dimensions, stand- 

 ing as an island, in post-pliocene times, in the sea, shows by the configuration 

 of its base that an oscillation averaging about 20 feet in vertical height has 

 taken place, the country being depressed and afterwards raised to about the 

 same altitude again. This line is well visible travelling round Banks Penin- 

 sula to its western termination, where, when we reach that altitude above the 

 sea level, the signs of a former submersion disappear below the newer fluvia- 

 tile and lacustrine deposits. 



During and after the small submergence of its base, this portion of Banks 

 Peninsula was of course subjected to the fury of the waves, when in favourable 

 localities caves were formed, either by the removal of loose material (tufas) 

 between two harder lava streams, or by the enlargement of pre-existing 

 hollows, such as are found as air bubbles, often of gigantic size, in lava 

 streams running generally parallel to the direction of their flow. 



In this instance there is no doubt that the Moa-bone Point Cave is a pre- 

 existing hollow in a doleritic lava stream, which has been enlarged by the 

 enormous power of the clashing waves of the ocean beating here at one time 

 furiously against the northern foot of the Peninsula. 



In previous publications (amongst others, " Report on the Formation of 

 the Canterbury Plains, 1864," page 22, et seq.) I have shewn how in post- 

 pliocene times from the material brought down by the enormous glacier 



torrents, forming huge shingle fans at the foot of the glaciers, two bars were 

 thrown across the sea ; one to unite the northern, or Waimakariri-Ashley de- 

 posits, with the northern slopes; another to connect the southern or Rakaia- 

 Ashburton beds of the same nature with the southern slopes of Banks Penin- 

 sula, behind which a huge lake was formed, of which Lake Ellesmere is the 

 last remnant. Of the northern bar we can trace the inner or western shores 

 through Kaiapoi to the neighbourhood of Woodend. 



In this large fresh-water lagoon (occasionally an estuary basin) the "Wai- 

 makariri, Selwyn, and sometimes the Rakaia discharged their waters, having 

 an outlet near the north-western slopes of Banks Peninsula, of which, in going 

 towards Cashmere, the residence of Sir Cracroft Wilson, we can easily trace 

 the lines of dunes and shingle by which the eastern shore of that lake was 

 formed, being in the beginning very narrow, and only gradually, as more and 

 more material was added, assuming a greater breadth. Thus we are able to 



:hbourhood 



