Around 30 milion years ago, the fossil environment of the Chiavon Bianco introduced completely different characteristics from those that we can find these days. The greatest part of the rests that were found, between fishes and plants, currently lives in the coastal waters of the Indo Pacific ocean, in the Oriental Coast of Africa up to the Indo-Australian area. The climate that characterized the Chiavon's area during the Middle Oligocene corresponds to the climate that characterize these zones nowadays: a climate partially tropical (dry-humid) and partially equatorial. The ittiofauna oligocenica of the Chiavon also introduces kind of moderate climate. The fossils sedimentation environment had to be a small basin of dimensions similar to a bay harbor, of coastal environment in which contributions terrigenis reached elegant granulometria, that had origin from an area emerged in the north (the Alps). From the south the basin communicated with the open sea while the proximity of sources of fresh water is characterized from abundant phyllites of continental origin. The waters of the bay lodged fishes planctofagi and predatory fishes coming from the open sea, besides molluscs, shellfishes and echinodermi. The vegetation of the area was made up by different communities that populated the basin while emerged land were covered by tropical forests and beaches that entertained numerous palm groves. The stability of the organisms and the spieces that populated the marine habitat of the bay was guaranteed from the absence of vertical circulation of water: the deep waters, poisonous, remained separate from the superficial waters, well oxygenate and rich of nourishments. The superficial waters hosted a big amount of planctofaghe spieces that were found in the area and were destinated to be plundered by fishes that lived in the open sea. In the paleographic environment the volcanic eruptions constituted devastating and traumatic events for all the lifeforms: improvise events of this type seems to have been the cause of the poisoning of the marine habitat of the Chiavon Bianco bay. The volcanic eruption caused the ascent of anoxic and rich of H2S waters from the deepest zones until the surface, causing the death of the fishes. In this environment numerous organisms found good conditions for the process of fossilization and maintenance in the sea backdrops.