406 Transactions. — Geology. 



covered with bush, through which the Awaroa Creek meanders, are part of 

 the former estuary, which the river has gradually almost filled up with 

 masses of sand, mud, and pumice stone, which it always carries along," to 

 which I add, aided by the gradual rising of the land. 



This period was subsequent to the depression referred to in Mr. James 

 Stewart's interesting paper "On the evidence of recent changes in the 

 elevation of the Waikato district," and the old shingle beach therein 

 referred to as having been found in sinking for the cylinders of Ngaruawahia 

 bridge is probably of date coeval with, or prior to the grand elevation which 

 took place when Tongariro and Kuapehu first exerted then- powers. The 

 evidence of changes in the physical geography of the Waikato and Thames 

 valleys are so numerous and so interesting from the surface and geologists' 

 point of view that a whole volume might be written on the subject, but as 

 this paper only deals with coastal changes, I will merely quote from the 

 " Transactions " and Hochstetter, two extracts, as bearing out the view 

 that the Thames valley was recently occupied by the sea. The latter says, 

 in referring to these two valleys, — " This whole basin was previous to the 

 last elevation of the North Island, which was probably connected with the 

 volcanic eruptions in the centre of the island, a bay of the sea, extending 

 from Hauraki Gulf far into the interior. The steep margins of the sur- 

 rounding ranges has continued to this day displaying the sea-shore of old, 

 and the singular terrace formation on the declivities of the hills and the 

 river-banks within this basin, is the result of a slow and periodical upheav- 

 ing ;" and again, at page 313, he says, — " These and similar strata seem to 

 point to the fact that the whole of the Waikato basin was, but recently, a 

 shallow bay of the sea, or a far extending estuary, at the bottom and on 

 the margins of which these layers of shale were formed." Mr. Kirk supports 

 this opinion of the sea having recently occupied the Waikato basin by refer- 

 ence to the maratime plants found there. Captain Hutton, however, in a 

 paper " on the alluvial deposits of the Lower Waikato and the formation of 

 islands by the river," rather combats this idea, at all events as respects the 

 Lower Waikato. He says, — "There appears therefore no geological evidence 

 of the sea having been in the lower basin of the Waikato since the upheaval 

 of the Waitemata series, that is, since it had any existance. I therefore 

 think that the fact of the pressure of several littoral plants in the Lower 

 Waikato basin, brought forward last year by Mr. Kirk, may be best ex- 

 plained by supposing that they have spread down the river from the middle 

 Waikato basin, after the formation of the Taupiri Gorge." 



Passing now to .the southwards of Cape Colville in our coastal survey, 

 we shall find the same evidence of elevation of about 15 feet, with, in addi- 

 tion, an older line of elevation, averaging from 80 to 100 feet. Those who 



