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The Cenozoic Era

At the end of the Secondary Period and at the beginning of the Tertiary Period, shallow water marine sedimentation was prevailing. Calcium carbonate rocks were abundant, related with biologic activity common in tropical seas.

Cenozoic rocks (except the Quaternary):

Transition from Mesozoic to Cenozoic involved great changes in life on Earth. Large reptiles, among other groups, were extinguished, giving an opportunity to mammals../p>

The Earth, 60 million years ago.

In Sobrarbe, those changes are represented in the fossils of the marine origin rocks from Paleocene. During the Eocene and Oligocene, the most important stages in the Pyrenees formation took place, as well as the sedimentation, mainly detritic, refills the Aínsa - Jaca Basin. This basin developed on the Cotiella dipping fault and most of its sediments came from east and south-east, until the Pyrenean relief emerged sufficiently as to provide new sediments from north and south.

When the sea withdrew, at the end of the Eocene, sedimentation was distinguishable by transition environments (Sobrarbe Delta) until it became finally continental.

Turbidites in the Corteroles Gorge. (Municipality of Labuerda) Sedimentary detritic rocks originated during the deep sea domain in the Eocene basin.

From the Oligocene, erosive processes have prevailed in this region. At the end of the Miocene, the Ebro River flowed to the Mediterranean Sea and the erosive process intensified. In the limestone massifs, karstic processes developed, and they still continue until the present day.

Turbidites in the Aínsa Channel (sandstone quarry by Aínsa).

Some of the most outstanding events in this period are: the great diversification of mammals, birds and primates, the appearance of whales and the first hominids.