ARTICLES
How Earth’s Continents became twisted and contorted over millions of years (continued)
The East African Rift valley is one of the most spectacular
examples of crustal extension visible at the surface. It has not
subsided below sea level because the region is being pushed
up by a mantle plume, a large upwelling of hot molten material
causing uplift and volcanism.
The rift valley is underlain by a giant fault system that is splitting
Africa in two. The rift turned a flat landscape into one with 4km
high mountains and lake basins with vegetation ranging from
desert to cloud forest. This variety of surface environments paved
the way for the early evolution and diversification of humans.
Present day map showing the areas that have undergone
compression or extension during the past 250 million years.
Deformed continental regions include large stretched and
submerged continents like Zealandia, as well as crustal
contraction where collisions have occurred, producing mountain
belts such as the Himalayas, the European Alps, Iran’s Zagros
Mountains and the southern Alps of New Zealand.
The Rift Valley was an important site for early evolution and
diversification of humans.
The importance of stress
We may not like stress in our daily lives, but the continuous stress
and strain acting on continents provides us with an important
record of Earth’s history.
Modelling the patterns of continental deformation through
time allows us to explore regional patterns of earthquakes and
volcanism and explain dramatic changes in Earth’s climate over
time.
Folded marine sediments on the Whangaparaoa Peninsula
north of Auckland, New Zealand, reflecting the formation of
a convergent plate boundary in northern New Zealand in the
beginning of the Miocene Period, around 23 million years ago.
It also provides a framework based on tectonic data to seek
mineral resources such as the metals cobalt and tungsten, which
are needed for a sustainable energy future.
This reflects the formation of a convergent plate boundary in
northern New Zealand in the beginning of the Miocene Period,
around 23 million years ago.
The Science Teachers’ Association of NSW and “Science
Education News” sincerely thank ‘The Conversation’ for
encouraging republication of its articles, all having been written
by academics or PhD students who are experts in their fields.
SEN is also most grateful to the authors of this article, Dr Dietmar
Müller, Maria Seton and Sabin Zahirovic, for their endorsement of
this policy, as well for this really fascinating article. – Ed.
The cradle of humankind
When crust is being thinned and stretched, the crustal contortions
are usually hidden away from view because they are quickly
covered up by sediments. But there are exceptions.
34
SCIENCE EDUCATIONAL NEWS VOL 68 NO 3