commit 7e35bec83dd5d7e56331debc16cc0e713a141a61
parent 57abb7ecb1fa49d922cad3dd5122bfa87c9f0079
Author: Anders Damsgaard <anders@adamsgaard.dk>
Date: Tue, 29 Oct 2019 17:30:56 +0100
Work on intro
Diffstat:
1 file changed, 17 insertions(+), 13 deletions(-)
diff --git a/continuum-granular-manuscript1.tex b/continuum-granular-manuscript1.tex
@@ -61,19 +61,23 @@ Deep deformation is most likely in tills with relatively high hydraulic permeabi
\section{Introduction}%
\label{sec:introduction}
-Fast glacier and ice-sheet flow often ocurrs over weak sedimentary deposits, and basal slip accounts for nearly all fast ice movement \citep[e.g.,][]{Cuffey2010}.
-
-Basal sediments, called subglacial till, commonly consist of a poorly sorted mix of reworked older sediment and erosional products.
-\citet{Hooke1995} demonstrated that the grain-size distribution is fractal.
-Water is generated at the ice-bed interface because of frictional heating, and saturates the sediment pore space.
-The pore-water pressure relieves some of the overburden ice weight, so that the compressive stress on granular skeleton is reduced to Terzaghi's effective stress \citep{Terzaghi1943}.
-
-
-The dynamics of the basal interface is not well understood.
-Many sweeping assumptions.
+Fast glacier and ice-sheet flow often ocurrs over weak sedimentary deposits, where basal slip accounts for nearly all movement \citep[e.g.,][]{Cuffey2010}.
+Basal sediments, called subglacial till, are diamictons commonly consisting of reworked sediments and erosional products \citep[e.g.][]{Evans2006}.
+%\citet{Hooke1995} demonstrated that the grain-size distribution is fractal.
+Water is typically generated at the ice-bed interface because of frictional heating, and fully saturates the pore space.
+The pressure of the pore-water relieves some of the overburden ice weight, reducing the compressive stress on granular skeleton to Terzaghi's effective stress \citep{Terzaghi1943}.
+Water viscosity does not significantly contribute to critical-state shear stress.
+\citet{Iverson2010} reviewed the possible viscous contributions during sediment dilation and compaction but deemed them to be of minor importance.
+
+Early on, \citet{Boulton1987} presented observations of in-situ deformation of subglacial till and concluded that till rheology was mildly non-linear viscous.
+However, \citet{Kamb1991}, \citet{Iverson1998}, and \citet{Tulaczyk2000} demonstrated from laboratory shear tests that rate-independent Mohr-Coulomb plasticity is a far better rheological description.
+In spite of vaning observational basis, viscous rheologies did not fall out of favor as they allow for mathematical modeling of till deformation patterns.
+In particular, the rheology was used to explain subglacial landform formation \citep[e.g.,]{Hindmarsh1999, Fowler2000}, water drainage localization \citep[e.g.][]{Walder1994}, and ice-sheet mass loss \citep[e.g.,][]{Pollard2009}.
+\citet{Ritz2015} demonstrated that the assertion of basal behavior heavily influences future Antarctic contributions to global-mean sea level rise in ice-sheet models
We know that the assumptions matter, but not what to replace them with.
-
-% Early on, \citet{Boulton1987} concluded that subglacial till behaved mildly-non-linear viscous.
+However, the dynamic interplay of ice, water, and sediment is still not well understood.
+Small-scale laboratory experiments have provided revolutionary insights into till mechanics \citep{Iverson2015}, but few of the discovered sediment processes have found their way into numerical ice-sheet models.
+In particular, sediment advection during shear is
Here comes you!
Shed new unique light on this matter with a model that is related to granular-scale mechanics, but can be applied in an ice-sheet kind of setting.
@@ -87,7 +91,7 @@ Building on new modeling advances in granular mechanics.
% For example, paraphrase a sentence or two from each abstract.
% Organize the review so that it leads up to something, namely, my claim.
-Fast ice flow is often ocurring over weak sedimentary beds \[e.g.,][]{Kamb1991, Cuffey2010}.
+Fast ice flow is often ocurring over weak sedimentary beds \citep[e.g.,][]{Kamb1991, Cuffey2010}.
Early on, \citet{Boulton1987} concluded that subglacial till behaved mildly-non-linear viscous.
