Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stress relief caused Giant’s Causeway

28.01.2002


Ireland’s huge hexagonal columns are a natural consequence of lava cooling.


The Giant’s Causeway.
© Allan Davies / LGPL



The Giant’s Causeway is not the work of men or monsters, but a natural consequence of how lava cools and solidifies, new computer simulations suggest.

The causeway is a field of roughly hexagonal basalt columns up to 40 feet high on the shores of County Antrim in Northern Ireland. It arose when a flow of volcanic rock split into hexagonal columns to relieve stress, according to Eduardo Jagla of the Centro Atómico Bariloche in Argentina and Alberto Rojo of the University of Michigan in Ann Arbor1.


Viscous lava shrinks as it cools, so rock in a solidifying layer is pulled in all directions at once, the researchers explain. This sets up stresses like those that make paint crack or wrinkle. As this stress increases, cracks appear.

As the causeway’s 40,000 pillars formed, cracks in the solid layer above would have propagated down into the solidifying layer below, like a stack of paint layers drying one after another. These cracks would have been deflected along the way onto new courses that provided the greatest stress relief.

Cracks that form a hexagonal network reduce energy more effectively than randomly orientated cracks, say Jagla and Rojo.

If this idea is correct, the causeway’s hexagonal columns were created by a much more random vertical-cracking structure, which once stood over the columns but has since been eroded by wind, rain and sea. There is geological evidence that the causeway we see today is merely a part of an original solidified lava field.

They might be giants

When the Giant’s Causeway was first reported to the Royal Society in London in 1693, some wondered whether men had created the step-like stone columns with picks and chisels. Local legend attributes them to the Irish giant Finn McCool, said to have wanted to walk to Scotland without wetting his feet. The more prosaic lava-flow explanation was put forward in 1771.

The columns form a natural stairway from a cliff into the sea. All have between four and eight sides, but most are roughly hexagonal. This geometric regularity has perplexed scientists for centuries.

Jagla and Rojo support their idea with computer simulations of fracture patterns in a layer of particles joined by springs, which mimic the mutually attractive atoms in the rock. The researchers simulate shrinking and cracking in a series of particle layers, using the final cracking pattern in one layer as the starting point for the cracking of the layer below.

They find that the pattern evolves from one that has many randomly distributed cracks to one in which the fractures define large polygons, most of which are six-sided.

What’s more, the model correctly predicts the proportions of columns with different numbers of sides and the average cross-sectional areas of these columns.


References

  1. Jagla, E. A., Rojo, A. G. Sequential fragmentation: the origin of columnar quasihexagonal patterns. Physical Review E, 65, 026203, (2002).


PHILIP BALL | © Nature News Service
Further information:
http://www.nature.com/nsu/020121/020121-15.html

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>