Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

A frost "buzzsaw" mechanism for erosion of the eastern Southern Alps, New Zealand

Hales, Tristram ORCID: and Roering, J. J. 2009. A frost "buzzsaw" mechanism for erosion of the eastern Southern Alps, New Zealand. Geomorphology 107 (3-4) , pp. 241-253. 10.1016/j.geomorph.2008.12.012

Full text not available from this repository.


In the Southern Alps, New Zealand, large gradients in precipitation (< 1 to 12 m year− 1) and rock uplift (< 1 to 10 mm year− 1) produce distinct post-glacial geomorphic domains in which landslide-driven sediment production dominates in the wet, rapid-uplift western region, and rockfall controls erosion in the drier, low-uplift eastern region. Because the western region accounts for < 25% of the active orogen, the dynamics of erosion in the extensive eastern region are of equal importance in estimating the relative balance of uplift and erosion across the Southern Alps. Here, we assess the efficacy of frost cracking as the primary rockfall mechanism in the eastern Southern Alps using air photo and topographic analysis of scree slopes, cosmogenic radionuclide dating of headwalls, paleo-climate data, and a numerical model of headwall temperature. Currently, active scree slopes occur at a relatively uniform mean elevation ( 1450 m) and their distribution is independent of hillslope aspect and rock type, consistent with the notion that frost cracking (which is maximized between − 3 and − 8 °C) may control rockfall erosion. Headwall erosion rates of 0.3 to 0.9 mm year− 1, measured using in-situ 10Be and 26Al in the Cragieburn Range, confirm that rockfall erosion is active in the late Holocene at rates that roughly balance rock uplift. Models of the predicted depth of frost activity are consistent with the scale of fractures and scree blocks in our field sites. Also, vegetated, paleo-scree slopes are ubiquitous at elevations lower than active scree slopes, consistent with the notion that lower temperatures during the last glacial advance induced pervasive rockfall erosion due to frost cracking. Our modeling suggests temporally-averaged peak frost cracking intensity occurs at 2300 m a.s.l., the approximate elevation of the highest peaks in the central Southern Alps, suggesting that the height of these peaks may be limited by a “frost buzzsaw.”

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Sustainable Places Research Institute (PLACES)
Subjects: Q Science > QE Geology
Uncontrolled Keywords: Southern Alps; Periglacial processes; Frost buzzsaw; Scree
Publisher: Elsevier
ISSN: 0169-555X
Last Modified: 17 Oct 2022 10:10

Citation Data

Cited 75 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item