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 Turbulence creates ice in clouds
08.11.2019 | Leibniz-Institut für Troposphärenforschung e. V.

nachricht Manganese nodules: project on environmental impact during deep sea mining
08.11.2019 | Jacobs University Bremen gGmbH

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New opportunities in additive manufacturing presented

Fraunhofer IFAM Dresden demonstrates manufacturing of copper components

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...

Im Focus: New Pitt research finds carbon nanotubes show a love/hate relationship with water

Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.

New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

Im Focus: A new quantum data classification protocol brings us nearer to a future 'quantum internet'

The algorithm represents a first step in the automated learning of quantum information networks

Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...

Im Focus: Distorted Atoms

In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.

An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

Smart lasers open up new applications and are the “tool of choice” in digitalization

30.10.2019 | Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

 
Latest News

Theoretical tubulanes inspire ultrahard polymers

14.11.2019 | Materials Sciences

Can 'smart toilets' be the next health data wellspring?

14.11.2019 | Health and Medicine

New spin directions in pyrite an encouraging sign for future spintronics

14.11.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>