Profile image
By Alton Parrish (Reporter)
Contributor profile | More stories
Story Views

Last Hour:
Last 24 Hours:

How the Giant’s Causeway and the Devils Postpile Formed

Monday, April 16, 2018 0:17
% of readers think this story is Fact. Add your two cents.

A new study by geoscientists at the University of Liverpool has identified the temperature at which cooling magma cracks to form geometric columns such as those found at the Giant’s Causeway in Northern Ireland.

Geometric columns occur in many types of volcanic rocks and form as the rock cools and contracts, resulting in a regular array of polygonal prisms or columns.

Columnar joints are amongst the most amazing geological features on Earth and in many areas, including the Giant’s Causeway, they have inspired mythologies and legends.

Giant’s Causeway

Credit: University of Liverpool

One of the most enduring and intriguing questions facing geologists is the temperature at which cooling magma forms these columnar joints.

Liverpool geoscientists undertook a research study to find out how hot the rocks were when they cracked open to form these spectacular stepping stones.

In a paper published in Nature Communications, researchers and students at the University’s School of Environmental Sciences designed a new type of experiment to show how as the magma cools, it contracts and accumulates stress, until it cracks. The study was performed on basaltic columns from Eyjafjallajökull volcano, Iceland.

They designed a novel apparatus to permit cooling lava, gripped in a press, to contract and crack to form a column. These new experiments demonstrated that the rocks fracture when they cool about 90 to 140˚C below the temperature at which magma crystallises into a rock, which is about 980˚C for basalts.

This means that columnar joints exposed in basaltic rocks, as observed at the Giant’s Causeway and Devils Postpile (USA) amongst others, were formed around 840-890 ˚C.

Yan Lavallée, Liverpool Professor of Volcanology who headed the research, said: “The temperature at which magma cools to form these columnar joints is a question that has fascinated the world of geology for a very long time. We have been wanting to know whether the temperature of the lava that causes the fractures was hot, warm or cold.

“I have spent over a decade pondering how to address this question and construct the right experiment to find the answer to this question. Now, with this study, we have found that the answer is hot, but after it solidified.”

Dr Anthony Lamur, for whom this work formed part of his doctoral study, added: “These experiments were technically very challenging, but they clearly demonstrate the power and significance of thermal contraction on the evolution of cooling rocks and the development of fractures”.

Dr Jackie Kendrick, a post-doctoral researcher in the group said: “Knowing the point at which cooling magma fractures is critical, as –beyond leading to the incision of this stunning geometrical feature– it initiates fluid circulation in the fracture network.

Columnar joints in Iceland

Credit: University of Liverpool

“Fluid flow controls heat transfer in volcanic systems, which can be harnessed for geothermal energy production. So the findings have tremendous applications for both volcanology and geothermal research.”

Understanding how cooling magma and rocks contract and fracture is central to understand the stability of volcanic constructs as well as how heat is transferred in the Earth.

Professor Lavallée added: “The findings shed light on the enigmatic observations of coolant loss made by Icelandic engineers as they drilled into hot volcanic rocks in excess of 800 ˚C; the loss of coolant in this environment was not anticipated, but our study suggests that substantial contraction of such hot rocks would have opened wide fractures that drained away the cooling slurry from the borehole. Now that we know this, we can revisit our drilling strategy and further our quest for the new development of magma energy sources.”

The paper “Disclosing the temperature of columnar jointing in lavas” is published in Nature Communications (doi:10.1038/s41467-018-03842-4).

The research was funded by the European Research Council (ERC).

Contacts and sources:

University of Liverpool 


We encourage you to Share our Reports, Analyses, Breaking News and Videos. Simply Click your Favorite Social Media Button and Share.

Report abuse


Your Comments
Question   Razz  Sad   Evil  Exclaim  Smile  Redface  Biggrin  Surprised  Eek   Confused   Cool  LOL   Mad   Twisted  Rolleyes   Wink  Idea  Arrow  Neutral  Cry   Mr. Green

Top Stories
Recent Stories



Top Global

Top Alternative




Email this story
Email this story

If you really want to ban this commenter, please write down the reason:

If you really want to disable all recommended stories, click on OK button. After that, you will be redirect to your options page.