HexuK'xSOX. — Siirfdcr Fonn^ (iiid l)r<t nuific-xiinic m^ of (I f<f 3V/vo//. 315" 



(•1.) Tlie second cycle of erosion, though less complete than the first. 

 produced the lluvio -glacial Moutere drifts and the Old Man Bottom gravels, 

 and was initiated by the forcing-up of the peneplains and the consequent 

 reopening of the fractures. The Whakamarama peneplain was tilted to tlie 

 north-west and the Victoria peneplain to the west, and to this is due their 

 j^resent drainage. The higher elevation of the alpine peneplain caused its 

 western drainage to cross the Wainihinihi, Victoria, and Murchison pene- 

 plains where these abut against the alpine peneplain. The drainage of 

 the lower country, which dates back to this time, has been most profoundly 

 influenced by the great fractm'e-lines, especially in the alpine peneplain. 



(5.) The third, or present, cycle of erosion is very incomplete. Further 

 movement took place along the fracture-lines, and certain changes in the 



Art. XXX\'II. — The Mount Arrowsrnith District : a Study in Physiographic 



and Plant Ecology. 



Bv R. Speight. M.A., M.Sc, F.G.S. ; L. Cockayne, Ph.D., F.L.S. ; and 

 R. M. Laing, M.A., B.Sc. 



Plates III-Vll. 



TABLE OF CONTENTS. 



Part I. 



1. Introductoiy. 



2. Mountain systems. 



(a.) Topography. 



(b.) Relation to rainfall and conditions of erosion. 



(c.) Present form of mountain region — a dissected peneplain. 



3. Drainage systems. 



(a.) Relation to the structure of the country. 



(b.) The Rakaia Vallej-. 



(c.) The Lake Heron Valley : its features and origin. 



4. Lakes. 



{a.) Lake Heron: its general features, with special reference to the s]»its 

 now forming on its shores and to the action of shore ice. 

 0. Present glaciers. 



(a.) Cameron and Ashburton Glaciers. 

 (6.) Rakaia glaciers — 



(i.) Lyell Gla.cier. 

 (ii.) Ramsay Glacier, 

 (c.) Absence of terminal moraines from present glaciers. 



6. Former glaciation. 



(a.) General. 



(b.) Old moraines : their position and the arrangement of blocks forming 



them. 

 (c.) Ice-planed slopes. 

 (d.) Roches moutonnees. 

 (c.) Truncated and semi-truncated spurs. 

 (/.) Influence on the form of valleys. 

 [g.) Corrie glaciers in their relation to the formation of ]>asses and the- 



dissection of spurs. 

 (li.) Glacier pot-holes. 

 (/.) Efficiency of glaciers as eroding agents: Evidence furnished by the 



locality. 



7. Changes in drainage in the Rakaia Valley. 



8. Totara forest. 



