Lessons from the past
Ageing crust
Earth’s crust formed much earlier than previously
thought, show fragments from an African mountain
range with ancient rocks.
prompts questions
A
ccording to a recent study on
ancient magmatic rocks,
Earth’s continental crust started
evolving about 300 million years earlier
than previously thought. This finding
raises questions about the processes that
had shaped continents and distributed
metals between four and 2.5 billion years
ago, as well as about the exploration
for base and precious metals.
Most of the continental crust on Earth
is believed to have formed between four
and 2.5 billion years ago, known as the
Archaean Eon among geologists. Intense
and long-lasting volcanic action at that time
formed a proto-crust that broadly would
have resembled today’s oceanic crust.
In a study published in GeoScience
Frontiers, geology researchers from the
University of Johannesburg (UJ) show
that Earth’s continental crust started
evolving, or differentiating, 300 million
years earlier than previously understood.
“The earth developed from a seething
mass of magma, which is molten rock,
to the habitable planet we know now.
The traditional view saw crust formation
broadly as a process in three phases.
However, the new results indicate that
several cycles of thickening and m