Quantified time scale for glacial valley cross-profile evolution in Alpine mountains

Space is used as a proxy for time in determining the role of glaciation in shaping valley cross profiles in the Two Thumb Range (Southern Alps), New Zealand. The range is undergoing rapid tectonic transport and uplift as it is advected toward the Alpine fault. Repeated cycles of glacial erosion duri...

Full description

Saved in:
Bibliographic Details
Published in:Geology (Boulder) 2006-08, Vol.34 (8), p.637-640
Main Authors: Brook, Martin S, Kirkbride, Martin P, Brock, Ben W
Format: Article
Language:English
Subjects:
Australasia
Cenozoic
Deep Sea Drilling Project
DSDP Site 594
erosion
Geology
geomorphology
glacial erosion
glacial extent
glacial features
glaciation
Glaciers
IPOD
landform evolution
landscapes
Leg 90
morphometry
New Zealand
Pacific Ocean
Plate tectonics
quantitative geomorphology
Quaternary
Quaternary geology
reconstruction
regression analysis
Soil erosion
South Island
South Pacific
Southern Alps
Southwest Pacific
statistical analysis
theoretical models
time scales
Two Thumb Range
U-shaped valleys
Valleys
West Pacific
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Space is used as a proxy for time in determining the role of glaciation in shaping valley cross profiles in the Two Thumb Range (Southern Alps), New Zealand. The range is undergoing rapid tectonic transport and uplift as it is advected toward the Alpine fault. Repeated cycles of glacial erosion during the Quaternary have fashioned U-shaped valleys in the north of the range, close to the Main Divide, while valleys in the less glaciated south of the range have rounded divides and convex fluvial cross profiles. Tectonic transport and uplift rates, coupled with an offshore oxygen isotope (δ18O) record and glacial- geological reconstructions, allow time constraints to be applied to valley development along the range. Valley width and depth measurements and power-law equations were used to quantify the shape of cross-profile transects in 37 valleys. Valleys evolved into a characteristic U-shaped cross profile formed over ≥400 k.y. of glacial occupancy. This, regardless of other models of glacial flattening of valley long profiles, suggests that alpine glaciation excavates greater volumes of rock, indicating that glaciers are a more effective erosional agent than fluvial activity in alpine mountain belts.
ISSN:0091-7613
1943-2682
DOI:10.1130/G22700.1