The Garrotxa Volcanic Zone is situated 100 kilometres to the
north of Barcelona, an approximate road journey of two hours. It contains some
of the most interesting volcanic landscape in Europe. There are thirty
Strombolian volcanic cones, a few explosive phreatomagmatic craters, other
alternating Strombolian/explosive volcanoes and over twenty very unusually
constructed basaltic lava flows. In addition, the area’s moist Mediterranean
mountain climate has contributed to lush vegetation and a spectacular landscape.
Moves to give the volcanic zone legal status go back as far as
1917 but it was not until 1975 that a serious conservation campaign won
widespread support, culminating in protective legislation in 1982. A sharp rise
in urbanisation and industrial development in the area had begun to affect the
traditional rustic landscape. Volcanic craters were being used as civic refuse
disposal sites and a particularly grave threat to the survival of some of the
most interesting volcanoes was posed by cinder quarries taking material for use
in building block manufacture.
Volcanism is of a basic type, involving basanitic and basaltic
lava. The last dated eruption occurred 11,500 years ago, thus though volcanic
activity has ceased, it cannot be considered to be finally extinct. The volcanic
eruptions varied greatly in intensity owing to the characteristics of the
substratum crossed by the vent and especially because the magma encountered
layers of water-saturated materials.
The thirty or so volcanic cones are in a very good state of
natural conservation, considering their age. Most of the craters are visible and
consist of cinder material: scoriae and lapilli with intervening layers of
volcanic bombs. Pyroclastic hecciae are also visible, as well as cineritics and
base surge deposits.
At the Fontfreda cliffs, river erosion has revealed magnificent
prism-shaped columns while at Castellfollit, spectacular layers of lava from
different lava flows are superimposed creating a spectacular cliff with the
village sited at the top. At the 17,000 year-old El Croscat volcano, the lava
mass has a rough surface covered with lava blocks and numerous blisters
(projecting gas bubbles).