Hill. — The Great Watrarapa : A Lost River. 



431 



the extension. At the time when this condition existed the general slope 

 and river system of the Island were very different from what is now the 

 case. The slope was generally to the east by south, and the Ruahine, Ka- 

 weka, and Titioktira Ranges had not then reached their present elevation. 

 The volcanic district was directly associated in slope and drainage with the 

 east side, and numerous tributary streams carried their burdens of shingle, 

 pumice, and vegetable material from the back inland country, and spread 

 them broadcast over basin-like areas in a river-valley of great length that 

 was in process of making by the slow elevation of what now constitutes 

 the chief axial structure of the Island. 



Fig. 3. — East Coast, showixg Plain-growth since Subsidence. Shading shows Plain- 

 growth — the Plains filled and fokjied since Subsidence shown on Fig. 2. 



In order to obtain a clear idea as to the surface features of the country 

 at the time under notice, map fig. 1 should be studied. It shows the probable 

 extension of the coast eastward beyond what can be seen in the dotted 

 lines of the present coast, and the various streams that now constitute 

 different river systems are seen to form one river that had its head-waters 

 in the back country to the westward of Poverty Bay. Out in the ocean 

 to the south-east of Poverty Bay the river made a bend to the south by 

 west, and proceeded past the Mahia, through Hawke Bay, and south- 

 west into the valley now known as the Heretaunga Plain, and thence west 

 by south onward to the Wairarapa. On its course it received from the back 



