Cotton. — The Tuamaritia Valley. 



319 



(1.) While it cannot be determined whether subsidence took place slowly 

 or rapidly or by successive steps, it is certain that the subsidence was com- 

 pleted very recently. This follows from the fact that, while the Sounds 

 are, in places, extensive sheets of water, and the rocks of the hillsides are 

 deeply weathered, marine erosion has nowhere developed cliffs and rock 

 platforms to any extent, except along the flood-plain remnants at the 

 valley-heads, where lines of low cliffs have been cut in the fluviatile gravels. 



Fig. 3. — Sketch-map of the TtrAMAniNA Vaixey. 



• (2.) Tidal currents, with an exception which will be noted later, are fairly 

 strong. In the entrance of Pelorus Sound the strength of the tide is 3 knots.* 



(3.) The area of land in the Sounds block is but little greater than that 

 of water. Hence the supply of waste cannot be great in comparison with 

 the area of deposition. 



For these reasons it seems fair to assume that the thickness of marine 

 deposits in the Sounds is not great. The maximum depth of water given 



* Admiralty Chart, New Zealand, sheet 5. 



