Browsing by Subject "STRATIGRAPHY"

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Open Access
Making the case for a formal Anthropocene Epoch: An analysis of ongoing critiques
(Newsletters on Stratigraphy, 2017-01-01) Zalasiewicz, J; Waters, CN; Wolfe, AP; Barnosky, AD; Cearreta, A; Edgeworth, M; Ellis, EC; Fairchild, IJ; Gradstein, FM; Grinevald, J; Haff, P; Head, MJ; do Sul, JAI; Jeandel, C; Leinfelder, R; McNeill, JR; Oreskes, N; Poirier, C; Revkin, A; Richter, DDB; Steffen, W; Summerhayes, C; Syvitski, JPM; Vidas, D; Wagreich, M; Wing, S; Williams, M
© 2017 The Authors. A range of published arguments against formalizing the Anthropocene as a geological time unit have variously suggested that it is a misleading term of non-stratigraphic origin and usage, is based on insignificant temporal and material stratigraphic content unlike that used to define older geological time units, is focused on observation of human history or speculation about the future rather than geologically significant events, and is driven more by politics than science. In response, we contend that the Anthropocene is a functional term that has firm geological grounding in a well-characterized stratigraphic record. This record, although often lithologically thin, is laterally extensive, rich in detail and already reflects substantial elapsed (and in part irreversible) change to the Earth System that is comparable to or greater in magnitude than that of previous epoch-scale transitions. The Anthropocene differs from previously defined epochs in reflecting contemporary geological change, which in turn also leads to the term's use over a wide range of social and political discourse. Nevertheless, that use remains entirely distinct from its demonstrable stratigraphic underpinning. Here we respond to the arguments opposing the geological validity and utility of the Anthropocene, and submit that a strong case may be made for the Anthropocene to be treated as a formal chronostratigraphic unit and added to the Geological Time Scale.
Open Access
Quantification of Peat Thickness and Stored Carbon at the Landscape Scale in Tropical Peatlands: A Comparison of Airborne Geophysics and an Empirical Topographic Method
(Journal of Geophysical Research: Earth Surface, 2019-12-01) Silvestri, S; Knight, R; Viezzoli, A; Richardson, CJ; Anshari, GZ; Dewar, N; Flanagan, N; Comas, X
©2019. The Authors. Peatlands play a key role in the global carbon cycle, sequestering and releasing large amounts of carbon. Despite their importance, a reliable method for the quantification of peatland thickness and volume is still missing, particularly for peat deposits located in the tropics given their limited accessibility, and for scales of measurement representative of peatland environments (i.e., of hundreds of km2). This limitation also prevents the accurate quantification of the stored carbon as well as future greenhouse gas emissions due to ongoing peat degradation. Here we present the results obtained using the airborne electromagnetic (AEM) method, a geophysical surveying tool, for peat thickness detection at the landscape scale. Based on a large amount of data collected on an Indonesian peatland, our results show that the AEM method provides a reliable and accurate 3-D model of peatlands, allowing the quantification of their volume and carbon storage. A comparison with the often used empirical topographic approach, which is based on an assumed correlation between peat thickness and surface topography, revealed larger errors across the landscape associated with the empirical approach than the AEM method when predicting the peat thickness. As a result, the AEM method provides higher estimates (22%) of organic carbon pools than the empirical method. We show how in our case study the empirical method tends to underestimate the peat thickness due to its inability to accurately detect the large variability in the elevation of the peat/mineral substrate interface, which is better quantified by the AEM method.