During the top Devonian (beginning of the 3^rd period of the primary era) when the fish (cuirasses) lived, the first vascular plants appeared, as well as grounds and fossils which have been in existence for 340 to 480 million years.

This is according to the estimates of palaeontologists and the expertise carried out by the laboratories of geology in the natural Faculty of Science of Montpellier in France. Another expert, Professor Simon De Heidelberg, and other studies made by the office of concentration and of such varieties of molluscs have said the period known is3^rd period of the primary era, these animals were carnivorous.  The fossils with lengthened form are Orthoceras and Ammonites, ancestors of the cuttlefish and squid; those with spiral form are genialities, ancestor of the aneorite and marine gastropod or snail of the sea.

  With the magnifying glass we notice a multitude of microfossils, which is unique to trilobites, and the lilies of the sea, which, with the snail shells, definitely visible to the naked eye, considering their size, would make these sediments in the Silurian, the period before the Devonian.

A progressive draining of the shallow waters (between 60 and 80 cm of water) that caused the gathering of these watery colonies, or an abrupt increase of the marine ground, without volcanic eruption.

The density of these plates is a little higher than that of marble. In two centimetres thickness, the coefficient of resistance is 10, 292 kilos by cm2, the some or point of impact, as well on conglomerate.