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The Role of Fluvial and Glacial Erosion in Landscape Evolution: The Ben Ohau Range, New Zealand
Author(s) -
Kirkbride Martin,
Matthews David
Publication year - 1997
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/(sici)1096-9837(199703)22:3<317::aid-esp760>3.0.co;2-i
Subject(s) - glacial period , fluvial , geology , denudation , physical geography , erosion , tectonic uplift , plateau (mathematics) , geomorphology , last glacial maximum , range (aeronautics) , glacier , paleontology , tectonics , structural basin , geography , mathematical analysis , materials science , mathematics , composite material
Abstract A morphometric comparison of valleys has been made for the Ben Ohau Range in the central Southern Alps of New Zealand. The range is undergoing rapid tectonic transport and uplift. The humid north of the range is a glacial trough‐and‐arête landscape, with a temperate glacial climate. The dry south has rounded divides and plateau remnants dissected by fluvial valleys. Assuming that space–time substitution allows today's spatial valley‐form transition to represent evolutionary stages in valley development, the tectonic history allows time constraints to be placed on the rate of transition to an alpine glacial landscape. Morphometric change has been quantified using hypsometric curves, and distance–elevation plots of cirque and valley‐floor altitudes. Ancestral fluvial valleys have less concave long profiles but are stepped at altitude owing to the presence of high‐level cirques and remnant plateau surfaces, and possess a low proportion of land area at low elevation. Increasing glacial influence is manifest as smoother, more deeply concave long profiles and U‐shaped cross‐profiles associated with a higher proportion of the land area at lower elevation. The full morphological transition has involved up to 2.4 km of vertical denudation over the 4 Ma lifetime of the mountain range, of which 80 per cent would have occurred by preglacial fluvial erosion. Combining the trajectory of tectonic transport with reconstructed glaciation limits and climatic history, it is indicated that about 200 ka of temperate glacial erosion produces recognizable trough‐and areête topography. Mean and modal relief increase where glacial activity is confined to cirques, but decrease when trough incision by ice becomes established as a dominant process in the landscape. © 1997 by John Wiley & Sons, Ltd.