What processes produced the basalt columns of the Giant’s Causeway?

Asked by: Ben Young

The origin of Giant’s Causeway in Northern Ireland is shrouded in myth & legend. But how did these interlocking basalt columns really come to exist? The process is called columnar jointing. It happens when a layer of molten lava gradually cools by a loss of heat through its surface.

What process formed the Causeway?

Formed 50 to 60 million years ago, during the Paleogene Period, the Giant’s Causeway resulted from successive flows of lava inching toward the coast and cooling when they contacted the sea.

What process creates basalt?

Basalts are formed by the rapid cooling of basaltic lava, equivalent to gabbro-norite magma, from interior of the crust and exposed at or very close to the surface of Earth. These basalt flows are quite thick and extensive, in which gas cavities are almost absent.

How was the basalt columns formed?

Basalt columns are created by the cooling and contracting of lava—made of 90% basalt—which causes the ground to crack into long, geometric columns. This process is called columnar jointing.

What are the columns of the Giant’s Causeway made from?

The Giant’s Causeway is made up of over 40 000 columns of basalt and, together with the wider Causeway Coast, tells the story of the sequence of events at the start of the Palaeogene period, some 60 million years ago.

How is the Giant’s Causeway made?

It developed between 50 to 60 million years ago when a flood of lava oozed from fissures in the earth. The molten rock cooled and contracted, cracking into a series of some 40,000 columns, mostly in near-perfect hexagonal shapes.

Why are giants causeway rocks hexagonal?

As lava cools, cracks within the material grow most efficiently at certain angles. In many places worldwide, such as Devils Tower in Wyoming and the Giant’s Causeway in Northern Ireland (image), ancient lavas cooled into hexagonal blocks or columns.

Why is it called giants causeway?

It’s called ‘The Giant’s Causeway’ because according to legend, it was actually the work of Irish giant Finn McCool who created it in order to cross Scotland so he could go into battle against his enemy Benandonner.

What environment is basalt formed in?

Basalt-Forming Environments



Most of the basalt found on Earth was produced in just three rock-forming environments: 1) oceanic divergent boundaries, 2) oceanic hotspots, and 3) mantle plumes and hotspots beneath continents.

Is basalt natural or manmade?

Basalt fibres are obtained from a naturally-occurring complex silica/alumina/other oxide basalt rock similar to glass in composition and used as an asbestos-replacement.

Is basalt igneous sedimentary or metamorphic?

Igneous rock

Igneous rock is formed when magma or lava from volcanoes cools. Examples include basalt and granite.

How are columns formed?

Columns can form in a variety of patterns, mainly hexagonal (but can be found with anywhere from 4-8 sides). They can vary in size from only a few centimeters to meters across. They form when a thick body of cooling magma (or even ash – see below) starts to contract and cracks begin to form.

How columnar structure is formed?

Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms, or columns. Columnar jointing occurs in many types of igneous rocks and forms as the rock cools and contracts.

How are basalt columns hexagonal?

Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons.

What type of rock is basalt columns made of?

volcanic rock

These columns of rock are most likely a volcanic rock called basalt. (Basalt makes up about 90% of all the lava rock on Earth.)

What type of rock is basalt made of?

basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in colour, and comparatively rich in iron and magnesium. Some basalts are quite glassy (tachylytes), and many are very fine-grained and compact.

Is the Giant’s causeway a volcano?

The Giant’s Causeway formed between 50 and 60 million years ago, when the region that now sits on the Antrim coastline was subject to intense volcanic activity. Molten basalt erupted through chalk beds and formed a lake of lava.

What makes a road a causeway?

A causeway is a track, road or railway on the upper point of an embankment across “a low, or wet place, or piece of water”. It can be constructed of earth, masonry, wood, or concrete.

Why are causeways built?

These causeways are often used to provide river crossings to link villages with neighbouring towns, but are often easily damaged because inadequate resources have been allocated to their construction.

What is a causeway system?

A causeway is a narrow raised pathway that has sand, marshland or water underneath it. Causeways may be a natural part of a landscape or they may be created with bridge construction methods. Some of these roadways may be a part of an irrigation system such as a canal.

What is a causeway in Egyptian culture?

The causeway was a long walkway that joined the valley temple and the mortuary temple. Although most of Khufu’s causeway is now gone, some of the blocks that made up the causeway can still be seen today. The causeway would have had walls decorated with painted reliefs and perhaps a ceiling with painted stars.

Who invented the causeway?

The Maya people created causeways up to 65 miles in length, crossing miles of forests in a nearly straight line.

What is a causeway used for?

Causeways: • For large stream or river crossings, bridge piers and footings are often located in the water, for this reason the contractor installs a causeway to gain access. A Cofferdam is a structure, generally of a temporary nature, constructed for the purpose of keeping water and earth out of the excavation area.