A new model for the Giant's Causeway

Weaire, D.; O’Carroll, Conor

doi:10.1038/302240a0

Cited by 17 publications

(7 citation statements)

References 3 publications

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“…These questions have been partly answered. Weaire and O'Carroll [1983] argue that the inward propagation of cracks is important in order to explain the statistical feature in polygonal geometry. Budkewitsch and Robin [1994] propose a self‐regulation model of the evolution of cracks that are initially randomly distributed at the cooling surface.…”

Section: Introductionmentioning

confidence: 99%

Columnar joint morphology and cooling rate: A starch‐water mixture experiment

Toramaru

Matsumoto

2004

J. Geophys. Res.

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[1] An analogue experiment using a starch-water mixture has been carried out in order to understand the effect of cooling rate on the morphological characteristics of a basalt columnar joint. If the contraction of material is essential for the formation of columnar joint structure, the water loss rate by desiccation (hereafter referred to as desiccation rate) in the experiment is analogous to the cooling rate in solidifying basalt. In the experiment the desiccation rate is controlled by varying the distance between the starch-water mixture and a lamp used as the heat source. We find that there are three regimes in the relation between joint formation and desiccation rate: (1) At desiccation rates higher than $1.4 Â 10 À2 (g cm À2 h À1 ) (normal columnar joint regime), the average crosssectional area S of a column is inversely proportional to the average desiccation rate, h. (2) Between that desiccation rate and a critical desiccation rate, 0.8 Â 10 À2 (g/cm 2 h), S approaches infinity as h _ M i decreases close to a critical desiccation rate (i.e., exponent d monotonically increases from unity to infinity) (critical regime). (3) Below the critical desiccation rate, no columnar structure forms (no columnar joint regime forms). Applying the present experimental result to the formation of basalt column, the basalt columnar cross-sectional area is inversely proportional to the cooling rate with factors including elasticity, crack growth coefficient, thermal expansion, glass transition temperature, and crack density ratio at stress maximum. Also, it can be predicted that there exists a critical cooling rate below which the columnar joint does not form; the presence of a critical regime between the normal columnar jointing and no columnar jointing during a certain cooling rate range can also be predicted. We find that at higher cooling rate the preferred column shape is a pentagon, whereas at lower cooling rate it is a hexagon.

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Section: Introductionmentioning

confidence: 99%

Columnar joint morphology and cooling rate: A starch‐water mixture experiment

Toramaru

Matsumoto

2004

J. Geophys. Res.

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“…These geomorphological features are manifestations of structures controlled by joints and layering in the rocks. Known occurrences of columnar basalts (Kantha, 1981;Weaire & O'Carroll, 1983;Wang et al, 2005;Goehring & Morris, 2008;Hofmann et al, 2015) belong to this subclass, because of sculpture-like view of these columns and their groups.…”

Section: Classification and Examplesmentioning

confidence: 99%

Aesthetics-based classification of geological structures in outcrops for geotourism purposes: a tentative proposal

et al. 2017

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The current growth in geotourism requires an urgent development of classifications of geological features on the basis of criteria that are relevant to tourist perceptions. It appears that structure-related patterns are especially attractive for geotourists. Consideration of the main criteria by which tourists judge beauty and observations made in the geodiversity hotspot of the Western Caucasus allow us to propose a tentative aesthetics-based classification of geological structures in outcrops, with two classes and four subclasses. It is possible to distinguish between regular and quasi-regular patterns (i.e., striped and lined and contorted patterns) and irregular and complex patterns (paysage and sculptured patterns). Typical examples of each case are found both in the study area and on a global scale. The application of the proposed classification permits to emphasise features of interest to a broad range of tourists. Aesthetics-based (i.e., non-geological) classifications are necessary to take into account visions and attitudes of visitors.

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“…Columnar joints provide another example of a primary igneous flow porosity related to initial cooling of magma (DeGraff & Aydin 1993). The joints develop layer by layer in response to thermal stresses building up behind the solidification front (Weaire & O'Carroll 1983), and occur in both basaltic and acidic rocks, often where magma interacts with ponded water (Lyle, 2000). Columnar joints can be discontinuous and locally developed within a flow, or pervasive and penetrative throughout.…”

Section: Flow Porosity (Class F)mentioning

confidence: 99%

Controls on primary porosity and permeability development in igneous rocks

Petford

2003

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Some of the more important processes leading to the development of primary igneous porosity due to the cooling and crystallization of magma are reviewed. A distinction is made between volcanic and plutonic rocks, and crystalline and granular volcanic material. Porosity in each rock type is classified according to a proposed effective length scale and geometry into diffusive (Class D) and macroscopic flow (Class F) features. Estimated ranges in values of porosity and permeability are given for a wide selection of igneous rock types, and comparison is made with permeability variations (Δk) derived for both the continental and oceanic crust. While fracture porosity is dominant in most crystalline materials, primary porosity development may play an important role in the final (total) porosity in igneous basement. Some types of primary porosity and permeability in igneous rocks will be strongly time- and scale-dependent due to thermal effects associated with the emplacement and cooling of magmas and volcanic material. Tectonic reworking of the primary petrophysical properties of basement-forming igneous rocks may be significant in the development of regions of anisotropy and enhanced porosity.

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A new model for the Giant's Causeway

Cited by 17 publications

References 3 publications

Columnar joint morphology and cooling rate: A starch‐water mixture experiment

Columnar joint morphology and cooling rate: A starch‐water mixture experiment

Aesthetics-based classification of geological structures in outcrops for geotourism purposes: a tentative proposal

Controls on primary porosity and permeability development in igneous rocks

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