Geonews

LATEST NEWS: The Giants Causeway
May 2016
GeoNEWS
In the Footsteps of Giants

The Giants
Causeway is
described in the 1985
UNESCO new
inscribed property
as a sea level
promontory carved by
the sea from the
lowest colonnade of
the Middle Basalts
between Port Ganny
and Port Noffer. It is
constituted of 3
promontories which
are the Grand, the
Middle and the Little
Causeways.
This place is known for

its 40,000 hexagonal
columns, gently inclined
or completely vertical.
One of the most
impressive formation is
The Organ. These
columns are due to the
slow cooling and
gradual contraction of
the basalt. The
resistance of this basalt
to marine erosion
explains the exceptional
preservation of the
place.
As can be seen on this

map of Northern
Ireland, the Giant
causeway is on a basalt
rocks area, which were
laid down around 60
million years ago, in the
Tertiary age. Those
basalts are due to the
cooling of tertiary lava.
The Antrim plateau
were the Giant's
causeway is located
was formed above big
cracks and fissures in
the earth's
crust.
Giants Causeway
!1
The work of a Giant ?

The Giants causeway is the
result of an important
volcanism activity that
occurred 62 millions years ago
in Antrim.
The Causeway is composed

of 40 000 basalts columns up
to 12 meters high. The lower
part of these columns is rich in
olivine, a green mineral. The
upper columns were formed
by rain and erosion. The site is
composed of columns
because lava was trapped in
valleys (which were dig by a
river) and cooled really slowly
then, it contracted and cracks

propagated in depth.
The size of the columns
depends on the time the lava
took to get cold.
Some of the rocks of the
Giant's Causeway are red (as
the ones in the photo). This
color comes from the
alteration of the rocks because
of the water or of the tropical
climate which present in this
era.
Ice during the ice age also
damaged the rocks and the
columns were a little bit higher
2 millions years ago.
This spectacular landscape

owes its existence to the
interactions of:
- A varied geology
comprising two major
episodes of superimposed,
Early Tertiary lava flows
separated by a thick palaeosol
suggestive of humid Tropical
like conditions, all of which are
cut through by numerous
dykes.
-A complex late- and postglacial history that saw ice
retreat from the area, sea level
rise and fall and the paraglacial adjustment of marine
cliffs to create, for example,
the many bays and the
extensive scree found along

the coast.
-The Long-term exposure of
the site to high-energy coastal
conditions that worked with
the underlying geology to
erode and emphasise the
distinctive embayed coastline
and are now actively attacking
the headlands they created.
-A long, and ongoing history of
human intervention including:
stone extraction, footpath
construction and road building,
the construction and
demolition of various buildings
and the running of a high
profile transport system.
!2
Solving the mystery of the hexagonal

column formations
The secret of the formation of the
Giant's Causeway was
discovered by physicists at the
University of Toronto.
Now they can predict the shapes

of other fracture networks such
as drying mud, cracking paint or
the patterns of fracture in
permafrost.
They used water, corn starch,

and a heat lamp to explain the
formation of hexagonal columns
forming this touristic site.
This simple experience

permitted to develop the study of
the cooling process of materials.
The key to understanding the

shape of the columns was to
reproduce the phenomenon in a
lab.
You need to mix water and corn
starch, then heat it all and
carefully control the drying
process.
Corn starch crack as it dries out
and forms very similar columns.
Then physicists established a
relationship between the size of
the columns and the speed at
which it cooled.
They observed that the columns
formed by the starch and the
columns formed by lava are the
same.
They also found the ratio of
speed, the slower the cooling
process, the larger the resulting
columns would be.
This ratio permitted a lot of
deduction about the cooling rate.
!3
!4

Geonews

Uploaded by

Copyright:

Available Formats

Geonews

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Geonews

Uploaded by

Copyright:

Available Formats

LATEST NEWS: The Giants Causeway

In the Footsteps of Giants

This place is known for

As can be seen on this

The work of a Giant ?

The Causeway is composed

then, it contracted and cracks

This spectacular landscape

extensive scree found along

Solving the mystery of the hexagonal

Now they can predict the shapes

They used water, corn starch,

This simple experience

The key to understanding the

You might also like