The last patches of snow cling for dear
life to this mountain slope of black tuff, near the Vatnajokull glacier in eastern Iceland.
Nature slowly resumes
its role in this abandoned basalt quarry near Kasbach, in the
German Eiffel region. Basalt is an extrusive, igneous rock, which
.means a rock solidified from lava that has ascended, by volcanism, to the earth's surface. Upon cooling the basaltic lava-body
shrinks, and then often sets in a pattern of elongated, five or sixsided columns. This geometrical form makes these basalts of
perfect use for cladding of dykes and other waterfront constructions and in the Eiffel region columnar basalt has been
exploited for this purpose since centuries, nearly to the point of
depletion. The next chapter also shows some striking examples
of such columnar basalts.
Dolerite is an 'intrusive' rock, meaning an igneous
rock that solidifies underneath the earth's surface. It is akin to
basalt, which however is an 'extrusive' rock, a rock that flows
out over the surface.The dolerites of the Pilbara region in West
Australia, as seen in this picture, form protrusions and elongate
dykes that jut out from the flat plains over large distances, their
deep-red crests tufted by softly green tussocks of spinifex grass.
II