Rock on, Alicante!
A brief geological history/main events/vocabulary,
and a bit of context for future articles
The Alicante province can be found at the eastern end
of the Betic Cordillera, a 600km mountain range which
occupies most of the southern and south-eastern parts
of the Iberian Peninsula.
The rocks here are mainly sedimentary, formed by
the accumulation of layers of sediments (loose bits of
anything and everything) in a big and often water-filled
dip in the ground (a sedimentary basin). Underneath
the sedimentary rocks there is what is known as the
basement and which is made up of ancient rocks which
are either igneous (made from magma) or metamorphic
(rocks which have been changed by heat and pressure).
So when and where these rocks were formed? And how
and when they were all crushed together and mushed up
to form the mountains we see today?
Jurassic limestones,
Cabeço d’Or, Busot
So let’s start with the basement, which we can’t actually see here in Alicante, but which we
know is the same as the basement everywhere else in the Iberian Peninsula and is made up
of metamorphic rocks left over from a tectonic collision (two big chunks of the earth’s surface
smashing together to make mountains which were then eroded away) about 300 million years ago.
After this there was an episode of extensional activity (a stretching and breaking apart of
the basement) which created the dip that we need to accumulate sediments and make our
sedimentary rocks. In each different part of the basin different types of rocks were formed.
The oldest sedimentary rocks we can see around this area are Triassic in age (200-250 million
years old). These are generally the brightly colored red, yellow and green rocks which can be
seen, for example, in the Monnegre
area just inland from Muchamiel.
They were formed in a very shallow,
and sometimes exposed, basin.
Cretaceous rocks, Cabeço d’Or, Busot
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A little bit later, in the Jurassic
(145-200 million years ago) the sea
level rose and the type of rocks
that accumulated on top of the
Triassic ones changed to be mainly
limestones such as the ones you
can see at the Cabeço d’Or in Busot,
or at Puig Campana in Finestrat.
This was later followed by another
extensional phase which broke this
shallow limestone platform of the
basin and created higher and lower
areas in the basin where different