The superimposed layer, which is sculptured, is generally opaque white.
Geologically, Armenia consists of archaic rocks upon which, towards the north, are superimposed Palaeozoic, and towards the south later sedimentary rocks.
The Blue Clay forms, at the higher levels, a stratum impervious to water, and holds up the rainfall, which soaks through the spongy mass of the superimposed coralline formations.
This last was rebuilt and enlarged in 1843-1844, but preserves the three bays of the Saxon church, with its western narthex, on which was superimposed the Norman tower, which presents its rich front to the street.
What came out below was a compact cylinder with a rounded bottom, consisting of so many layers superimposed upon one another.