During Oligocene lithoidal material, derived from Alps chain erosion, laid down into conoid-shaped alluvial fan, Delta regions or coastal.
With a thickness up to 1,500 m, Oligocene conglomerates belonging to the “Formazione di Molare” rise up along Langhe southern edges, giving scarce but interesting proofs of fossils presence, in particular Continental mammals remains. Conglomerates are then stratigrafically followed by “Formazione di Rocchetta” clays, with a thikness range between 300 and 500 m, which has been deposited in the sea. Their content in terms of fossils is very contained, but various (macro foraminifers, shellfishes, corals).
Miocene clays sedimentary rocks, usually alternated to sandstone layers, have been deposited in deep and open sea under the guide of turbidity currents and contains few fossils.
This geological period gave rise to formations which are physically different depending on sedimentary sea environment. Many of these formations got their name from Langhe places.
In particular, “Formazione di Cessole” section has been taken as the stratotype of the level named Langhiano.
Late Miocene ends with Messiniano, “facies” which gives a proof of the severe water crisis of proto-mediterranean basin.
To this particular perspective of Ending Miocene is dedicated showcase 5.
The formation of towns called Monesiglio, Cortemilia and Paroldo Marls all belong to this level of Early Miocene. We are talking of lithological unit developed from sea sediments, which has been deposited more than 1,000 m deep down in a period ranging from 23 to 16 mya.
Clay and marl layers show rich fauna microfossils, in particular benton foraminifera that lived in association with sea bottom.
Langhiano e Serravalliano
Langhiano e Serravalliano are two particular period of Middle Miocene (16-11 mya) in which sea sediments has been deposited, with a preponderance of marls and clays that reach a thikness of 2000 m. These sediments are responsible for Formazioni di Cassinasco, Cessole, Murazzano and Lequio.
It’s a geological period (11-7.2 mya) in which there is the deposition of the well known “Fossils Marls of Saint Agatha”. These, with a thickness of 400 m, give a proof of a sedimentation that has been occurred still in open and deep sea. Fossil Marls are rich in foraminifers, fish otoliths, sea urchin, shark teeth, while upper lamina bring ichthyolites (fishes skeletons) and phyllites (leaves imprint).
In Alba territory Tortoniano period also gave Gallo d’Alba Marls and Diano d’Alba Sandstone.