Abstract
Nature does not have a preferred size scale to reveal its wonders. From the synchronized dynamics of the solar system to the symmetry of a crystal lattice, every scale discloses new manifestations of the natural order.
Today, the appeal to the authority of experts is sometimes excused by the immensity of our specialized knowledge. [...] But in my view, the appeal to the authority of experts should be neither excused nor defended. It should, on the contrary, be recognized for what it is —an intellectual fashion— and it should be attacked by a frank acknowledgement of how little we know, and how much that little is due to people who have worked in many fields at the same time.
Sir Karl R. Popper (1994), p. x
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Notes
- 1.
Recovery and recrystallization are complex physical phenomena that are better understood if decomposed in a hierarchy of structural processes or mechanisms, here qualified as “elementary” and “phenomenological”. A somewhat similar hierarchical scheme for recrystallization has formerly been proposed by Drury and Urai (1990), but with the expressions “elementary/phenomenological process” replaced respectively by “basic process” and “mechanism”. We favour here the qualifiers “elementary/phenomenological” (against the “process/mechanism” scheme) because these qualifiers facilitate the visualization of the hierarchy and leave us free to use the terms “process” and “mechanism” as synonyms.
- 2.
Calculations show (Cahn 1970; Humphreys and Hatherly 2004) that classical nucleation recrystallization is extremely unlikely to occur in single-phase polycrystals, owing to the high energies required for the creation and growth of classical nuclei, except if strong chemical driving forces are present, which is clearly not the case for polar ice.
- 3.
The prefix “pseudo-” is used here to emphasize that this nucleus is usually much larger than the nucleus formed by classical nucleation, but still small enough to be strain-free. It should be noticed that the distinction between pseudo-nucleation and a combination of SIBM-O with rotation recrystallization is basically a matter of scale: in the latter case the new crystallite is large enough to inherit a considerable amount of internal structures from the parent grain.
- 4.
According to this definition, which derives from Kirchner and Faria (2009), the term “ice sheet” generally refers to “inland ice sheet and related ice shelves”.
- 5.
A detailed description of a logging procedure, in the case of the NorthGRIP Deep Ice Core, is presented by Hvidberg et al. (2002).
- 6.
More information on borehole deformation is available in several studies (e.g. Dahl-Jensen and Gundestrup 1987; Etheridge 1989; Garfield and Ueda 1976; Gundestrup and Hansen 1984; Ryser et al. 2014). For the particular case of the EDML borehole, see Weikusat et al. (2017).
- 7.
The definition adopted here is based on the concept of “grain-boundary migration recrystallization” originally described by Beck and Sperry (1950). Notice that this definition is identical neither to that used by Poirier (1985) nor by Humphreys and Hatherly (2004), and it is also quite distinct from some loose connotations invoked in the glaciological literature. The terms SIBM-N and SIBM-O are not standard in the literature, but they are nevertheless adopted here because they describe quite precisely the kind of information obtained from microscopic analyses of ice-core sections. There is unfortunately no one-to-one relation between SIBM-N/SIBM-O and the expressions “multiple/single subgrain SIBM” used e.g. by Humphreys and Hatherly (2004).
- 8.
As explained by Smith (1952), the interest in NGG comes from the fact that its kinetics depends solely on the properties of the migrating boundaries and is otherwise independent of the medium or its deformation history. This means that the theory underlying the NGG kinetics is not restricted to polycrystals: similar coarsening phenomena are also observed in foams, some tissues, and many other cellular media.
- 9.
In contrast to the definition adopted here, some authors reserve the term “recrystallization” solely for those processes driven by the stored strain energy, therefore excluding NGG (see normal grain growth) from its definition. Other authors (especially in the older literature) loosely use “recrystallization” as a synonym for SIBM-N (cf. migration recrystallization).
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Faria, S.H., Kipfstuhl, S., Lambrecht, A. (2018). Getting Started. In: The EPICA-DML Deep Ice Core. Frontiers in Earth Sciences. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-55308-4_1
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