Adkin. — The Horoivhenua Coastal Plain. 



115 



c. 



Fig. 2. — Diagrammatic sections showing the evolution of the Ohau Valley 

 in its fan about a mile below the fan's apex. 



a. Coastal-plain sandstone resting on the south-west slope of the Ohau fan. 



6. The cutting of the shallow valleys of the " Kimberley Road" Stream 



and the former Kuku Stream ; and the building of flood-plains 



(horizontal shading). 



The invasion of the Kuku Valley by the " Kimberley Road " Stream, 



and the removal of the right bank of the latter's former valley by 



the Ohau River flowing in its " north-west " course. 



Diversion of the Ohau River (at a point up-stream) into the original 



Kuku Valley, and its enlargement by the river. 

 The alluviation (black dots) of the valley of the Ohau (at this point) by 



gravels, &c., derived from the incision of the " valley plain." 

 The effect of lateral corrasion by the Ohau River after the alluviation. 



(Terrace or flood-plain gravels shown as open dots.) 

 Final deepening and terracing of Ohau Valley, resulting in its present 

 form. In the high terrace-face on the left a layer of sandstone lies 

 between the upper gravels (black dots) and the surface of the 

 Ohau fan. 



/• 



9 



