The role of lithospheric delamination and ice-driven rockfall erosion in the evolution of mountainous landscapes [microform]
- Bib ID:
- 4398321
- Format:
- Book and Microform
- Author:
- Hales, Tristram Charles
- Online Version:
- http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3251853
Broken link? let us search Trove , the Wayback Machine , or Google for you.
- Description:
- 137 p.
- Summary:
-
This dissertation discusses the evolution of mountains, particularly the interaction between uplift, which is controlled by horizontally-directed plate tectonic and vertically-directed isostatic forces, and erosion, which encompasses glacial, periglacial, fluvial and hillslope processes. Eruption of the Columbia River Basalts (CRB) in northeastern Oregon is coincident with rapid uplift of the Wallowa Mountains. I mapped the modern distribution of CRB flows to quantify the amount of post-eruptive uplift in northeastern Oregon, which creates a broad "bull's eye" pattern centered on a large granitic pluton. Rapid Wallowa Mountain uplift appears to be related to delamination of dense lower crust beneath the Wallowa batholith and is the likely cause of flood basalt volcanism at ~17 Ma B.P.
Rapid rockfall erosion rates in high mountains create extensive talus slopes. Parts of the Southern Alps, New Zealand, are dominated by kilometer-scale scree-mantled slopes which reduce hillslope gradients and decrease drainage densities. Field and aerial photograph-based analysis of scree slopes (i.e. rockfall deposits) reveal a peak in the areal extent and rate of scree slope formation in the eastern Southern Alps. This spatial distribution precludes earthquakes, postglacial stress release, and rock type as primary rockfall triggering mechanisms. Instead, scree slopes occupy a narrow elevation range across the New Zealand Alps and the mean elevation of scree slopes is consistent with a theory for rockfall initiation by frost cracking and segregation ice growth, a process that breaks rocks through surface interactions at the ice/rock interface.
Supported by data from the Southern Alps and other mountainous areas, I propose a simple numerical heat flow model to predict the climatic conditions and rock fracture spacing required for frost cracking. This model suggests that in highly fractured rocks the ultimate elevation of mountain peaks may be governed by the efficacy of frost action. This dissertation includes both my previously published and co-authored material.
- Notes:
-
- (UMI)AAI3251853
- Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 0844.
- Adviser: Joshua J. Roering.
- Thesis (Ph.D.)--University of Oregon, 2006.
- Reproduction:
- Microfiche. Ann Arbor, Mich. : University Microfilms International.
- Subject:
- Geology
- Other authors/contributors:
- University of Oregon
- Copyright:
-
In Copyright
Contact us for information about copying.
Copyright status was determined using the following information:
- Material type:
- Literary Dramatic Musical
- Published status:
- Unpublished
- Creation date:
- 2006
Copyright status may not be correct if data in the record is incomplete or inaccurate. Other access conditions may also apply. For more information please see: Copyright in library collections.
Request this item
Request this item to view in the Library’s reading room.