614 Transactions. 



Previous Investigations. 



As early as 1840 Dieffenbach* visited the locality, but that energetic 

 scientist Sir James Hectorf was apparently the first to examine the area 

 at all systematically. Later Mr. A. McKay,J the veteran geologist, carried 

 out further geological surveys. Dr. Marshall, § in recent papers, mentions 

 very briefly some features of the Aupouri geology. 



Physiography. 



At the northern part of the Aupouri Peninsula a low, much -dissected 

 tableland rises to a height of about 1,000 ft. This tableland seems to re- 

 present a portion of an old peneplain, which, formed in the Miocene period, 

 has been tilted in many directions and elevated to varying heights since 

 that time. 



The tableland occupies a great portion of the peninsula north of the 

 Harbour of Parengarenga. Southward of this inlet the tableland merges 

 gradually into lower country, showing less-pronounced rehef. Flat-topped 

 hills, gradually decreasing in altitude, border the eastern seaboard to Ho- 

 houra, where the more elevated country forming Mount Camel marks the 

 occurrence of an outcrop of harder and more ancient rocks. South of 

 Parengarenga sandhills extend inland from the western sea-coast, and, 

 south of Hohoura, cover the entire width of the peninsula. 



It will be apparent from the foregoing description that the peninsula 

 consists essentially of a northern rather rugged mass of hard igneous and 

 sedimentary rocks connected, by a long low tongue of less-resistant rocks, 

 to the main mass of the North Auckland Peninsula. The outhno of the 

 Aupouri Peninsula Vv^ould therefore seem to have been determined largely 

 by the varying character of the rocks that compose it. 



The sequence of events indicated by the present contour of the Aupouri 

 Peninsula is apparently similar to that which may be deduced from a study 

 of the physiography of the whole of the North Auckland Peninsula. 



The northern part of the Aupouri Peninsula has probably been subjected 

 to atmospheric denudation since the close of Miocene times, when it was 

 apparently reduced to a peneplain. Elevation since that time has caused 

 subaerial agencies to renew their work — a work now far advanced, as is 

 evidenced by the rounded contour of the hills, the general absence of rock- 

 waste, and the sluggish, well-graded character of most of the streams. In 

 comparatively recent times a depression has taken place, of which the 

 drowned river-valleys now forming the harbours of Hohoura and Parenga- 

 renga are the most striking evidences. A slight elevation may now be in 

 progress, but of this there is not as yet satisfactory evidence. 



The Land. 



The land - surface of the Aupouri Peninsula may conveniently be dis- 

 cussed under the following headings : (1) The tableland ; (2) the low hills 

 bordering the eastern seaboard ; (3) the sand country. 



* " Travels in New Zealand," 1843, p. 199. 



t " Geological Sketch-map of Northern District of Auckland." 



J Rep. G.S., 1894 : " On the Geology of Hokianga and Mongowii Counties, Northern 

 Auckland." 



§ " Distribution of the Igneous Rocks of New Zealand," Aust. Assn. Adv. Sci., 1907, 

 p. 366 ; " Geology of Centre and North of North Island New Zealand," Trans. N.Z. 

 lust., vol. xl, p. 79. 



