Soil transport driven by biological processes over millennial time scales

Research Article| December 01, 2002 Soil transport driven by biological processes over millennial time scales Joshua J. Roering; Joshua J. Roering 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272, USA Search for other works by this author on: GSW Google Scholar Peter Almond; Peter Almond 2Soil, Plant, and Ecological Sciences Division, P.O. Box 84, Lincoln University, Canterbury, New Zealand Search for other works by this author on: GSW Google Scholar Philip Tonkin; Philip Tonkin 2Soil, Plant, and Ecological Sciences Division, P.O. Box 84, Lincoln University, Canterbury, New Zealand Search for other works by this author on: GSW Google Scholar James McKean James McKean 3Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand Search for other works by this author on: GSW Google Scholar Author and Article Information Joshua J. Roering 1Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272, USA Peter Almond 2Soil, Plant, and Ecological Sciences Division, P.O. Box 84, Lincoln University, Canterbury, New Zealand Philip Tonkin 2Soil, Plant, and Ecological Sciences Division, P.O. Box 84, Lincoln University, Canterbury, New Zealand James McKean 3Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand Publisher: Geological Society of America Received: 22 Apr 2002 Revision Received: 26 Aug 2002 Accepted: 04 Sep 2002 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (12): 1115–1118. https://doi.org/10.1130/0091-7613(2002)030<1115:STDBBP>2.0.CO;2 Article history Received: 22 Apr 2002 Revision Received: 26 Aug 2002 Accepted: 04 Sep 2002 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Joshua J. Roering, Peter Almond, Philip Tonkin, James McKean; Soil transport driven by biological processes over millennial time scales. Geology 2002;; 30 (12): 1115–1118. doi: https://doi.org/10.1130/0091-7613(2002)030<1115:STDBBP>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Downslope soil transport in the absence of overland flow has been attributed to numerous mechanisms, including particle-by-particle creep and disturbances associated with biological activity. Process stochasticity and difficulties associated with field measurement have obscured the characterization of relevant long-term soil transport rates and mechanisms. In a series of incised fluvial terraces along the Charwell River, South Island, New Zealand, we documented vertical profiles of tephra concentration and topographic derivatives along a hillslope transect to quantify soil transport processes. Along the undissected hilltop, we observed a thin primary tephra layer (ca. 22.6 ka) within loess deposits ∼80 cm below the landscape surface. In the downslope direction, the depth to the highly concentrated tephra layer decreases, coincident with an increase in hillslope convexity (which is proportional to landscape lowering rate if soil flux varies linearly with hillslope gradient). Exhumation of the tephra layer results from landscape lowering due to disturbance-driven soil transport. Approximately 20 m downslope of the interfluve, the depth to the tephra layer declines to 40–50 cm, peak tephra concentrations decrease by a factor of 4, and tephra is distributed uniformly within the upper 40 cm of soil. The transition from a thin, highly concentrated tephra layer at depth to less concentrated, widely distributed tephra in the upper soil may result from soil mixing and transport by biological disturbances. Along our transect, the depth to this transition is ∼50 cm, coincident with the rooting depth of podocarp and Nothofagus trees that populated the region during much of the Holocene. Our observations can be used to calibrate the linear transport model, but, more important, they suggest that over geomorphic time scales, stochastic bioturbation may generate a well-mixed and mobile soil layer, the depth of which is primarily determined by flora characteristics. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.