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he central core of the Alps Throughout most of the age of dino- Along the southern shores of what
is granite. Mont Blanc, saurs, the Tethys Ocean, stretching would become Europe lay a shallow
for instance, was for- from the Massif Central to Tibet and tropical sea teeming with marine life.
T med when liquid magma, away to the south to what is now Beginning some 110 million years
usually found deep underground, North Africa, gradually became wi- ago the African continent began to
slowly solidified. It solidified be- der and deeper, accumulating layer drift northward towards Europe.
cause it came closer to the sur- upon layer of fine oceanic silt: a cen- As Africa pushed northward, first
face having been squeezed upward timetre in a 1,000 years, a metre in the sediment that had accumulated
by colliding continents. It cooled 100,000 years, a kilometre in 100 on the floor of the shallow tropical
because the overlying strata were
removed by erosion.

In geological terms, the Alps are
extremely young— about 25 mil-
lion years old. To situate this date,
remember that the last dinosaur
walked the Earth some 65 million
years ago. In simple terms, the Alps
were formed when Africa collided
with the southern part of Europe.

Throughout the history of the Earth
land masses have collided to form
mountain chains and separated to
form oceans. Mountain building
and erosion have been going on for
thousands of millions of years.

As the continents drifted across
the face of the Earth, the climate
has changed too. Some 250 million
years ago, the area now occupied
by Switzerland was a lowland tropi-
cal jungle. Over a long period, this
forest gradually dried out to become
savannah and then desert. For a very million years. As each successive sea was pushed up and over par-
long time, the desert endured with layer of sediment weighed down tially burying the Alpine area under
its red sand dunes and then slowly on top of previous layers, they were thousands of metres of limestone.
began to sink. The sea invaded and forced deeper into the Earth's sur- The rock of southern lands and seas
the surface continued to subside un- face where the pressure of what lay followed and, finally, parts of Africa
til it became the floor of a deep and above and heat from below changed piled in on top of everything else.
vast ocean. them into limestone. Each element of this multi-layered

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