better understand the regional geological setting of Cyprus, and
indeed the formation of Cyprus itself, one has to be
familiarised with the major principles of Plate
to the theory of Plate Tectonics, the surface of the Earth is
not made out of a single continuous crust but rather it is
divided into a small number of rigid pieces, the so-called Lithospheric
Plates (Fig. 1).
The major lithospheric plates of the Earth are the
American, the Eurasian, the Australian, the Pacific, the
Antarctic and the Indian (Fig. 2). These plates are in constant motion relative to each other
and form the following three main boundary types (Fig.
3): (a) Divergent boundary, along which the
plates are moving away from each other and in the space between
them new ocean crust is formed.
There is volcanic and seismic
activity along this type of boundary, with extrusion of lava
along the spreading axis and weak to moderate earthquakes.
An example of divergent plate boundary is the so-called
mid-Atlantic Ridge, where the African Plate moves away from the
American Plate; (b) Convergent boundary, along
which the two plates collide and one plate moves underneath the
other (subduction). The
volcanic and seismic activity in this type of plate boundary is
quite significant. An
example of convergent plate boundary is the Hellenic Arc and its
continuation towards Cyprus, where the African Plate collides
with the Eurasian Plate; (c) Transform boundary,
along which the two plates move parallel to each other but in an
opposite direction (the plates slide past each other).
No volcanic activity is observed along the transform
boundary (also known as transform fault zone), however this is
an area that produces catastrophic earthquakes.
A well-known example of transform boundary is the San
Andreas Fault on the west coast of the USA, which represents the
boundary between the Pacific plate to the west and the American
plate to the east. Figure 4 shows the positions
of volcanoes and earthquakes on the Earth.
Thus, the Earth is a dynamic planet that changes with geological time. New crust is created along the divergent plate boundaries, where submarine mountains, known as mid-ocean ridges, are formed. New oceanic crust can also be created above convergent plate boundaries, having an average thickness of 6 km. Our knowledge of the oceanic crust comes from geophysical surveys, drilling and submarine observations. However, the best means of studying the oceanic crust is by examining parts of it that have been uplifted (above sea level) and now constitute part of the land. Such on-land parts of oceanic crust are called Ophiolites and are usually found along convergent plate boundaries. The Troodos Ophiolite Complex in Cyprus is a good example of old oceanic crust.