406 Transactions. — Geology. 



occupy its present course directly across the plain, cutting 

 through a series of clay-ridges, whilst the fall of the country 

 from Cambridge is in a northerly direction. To subterranean 

 movements altering the surface- elevation of the land it is 

 evident these changes in the river's course are due ; and these 

 movements of elevation of the surface were of a paroxysmal 

 character, or, at least, too rapid to allow the river to erode its 

 channel deeper as the land rose. The evidences of elevation 

 and depression we have are numerous. Captain Hutton 

 proves submergence at the Thames by finding at a depth of 

 30ft. below sea-level, near Shortland, kauri-gum, raupo, and 

 pieces of wood. He continues as folio v/s : "It would thus 

 appear that when the alluvium full of boulders found on top of 

 the hills (near Shortland) was forming, the land was 1,000ft. 

 lower than at present ; that it then gradually rose until it was 

 100ft. higher than now ; and at that time the Thames ran 

 farther north than Shortland. The land then sank to about 

 10ft. or 12ft. lower than now, and subsequently has again 

 risen to its present level." I would here remark that when 

 the land at Hauraki was 1,000ft. lower than at present — 

 assuming that the movements of elevation and depression were 

 unequal in the different parts of the district (a supposition of 

 which we have some proofs, as shall bo shown later on) — the 

 Waikato Eiver w^ould flow down the Hinuwera Valley to the 

 Hauraki Gulf, which w^ould at that time extend far up the 

 valley. As the land rose until it was "100ft. higher than 

 now," probably the axis of elevation would be along the main 

 range from Cape Colville to Eotorua, w^ith a contemporaneous 

 subsidence to the south-west. The changes of level may be 

 supposed to have ponded back the Waikato Eiver into its 

 valley above Hinuwera until it had graded a new channel 

 through a pass in the Maungatautari Gorge. And the same 

 explanation may be applied to the phenomena in the Middle 

 Waikato basin. When the land in the Hauraki was " 1,000ft. 

 lower than now" the Middle Waikato basin was probably a 

 shallow bay of the sea. As the land rose along the main 

 range until it was 100ft. higher than now, the waters of the 

 Waikato were impounded in the middle basin, covering all the 

 lower areas of the valley as a shallow lake, which were then 

 filled with the alluvial deposits we find there now. The forma- 

 tion of the Taupiri Gorge would probably have taken place 

 at this period. The direct course of the Waikato Eiver from 

 Cambridge to Ngaruawahia, and the absence of a wide valley, 

 may be taken as indicating the rapid formation of the river- 

 bed, which was probably the result of the changes of level. 

 Mr. James Stewart, in his paper on "Evidences of Eecent 

 Changes of Level in the Waikato District," gives the follow- 

 ing : ' ' The proofs of subsidence we at present adduce are 



