River terraces and other geomorphic features, Castle Hill Basin, Canterbury, New Zealand

Abstract

Extensive systems of terraces in Castle Hill Basin are evidence for widespread cycles of aggradation and degradation of the rivers. The surfaces formed during periods of aggradation have been named as follows: Bridge Hill surface, Long Spur surface, Enys surface, Cheeseman surfaces and Post-Cheeseman surfaces. Evidence from moraines indicates that these aggradational surfaces were created during periods of glaciation when the streams of the valley were overloaded. Degradation and valley deepening ensued during non-glacial conditions, leaving the former river floodplains preserved as glacial terraces. The terraces ol' Castle Hill Basin have been correlated with similar surfaces in the Waimakariri Valley described by Dr. Maxwell Gage.