field geosciences teaching module: geoparks and geosites geopark naturtejo meseta meridional fossil...

Field Geosciences Teaching Module: Geoparks and GeositesGeopark Naturtejo Meseta Meridional

Fossil trees of Vila Velha de Ródão: How these fossils do enable to

recognize climate changes?

Geological Map of Naturtejo Global Geopark

Paleontological findings

Paleontological findings

The fossil trunks were found on the Monte do Pinhal terrace (T1) from Tejo river:

• It is the oldest (1,6 million years old)

• It has the highest position in relation with present riverbed (181m)

Fossil Trees of Vila Velha de Ródão in the Fossils Garden

Fossilization

After the death of the tree it was buried and the cells composing the plant fibres were filled by silica coming from dissolved silicate sediments - Permineralization.

Thousands of years

Silicified trunk

Why do the trunks have such color?

The fossils are older or the same age as the sediments where they were found?

Age of the fossil trunks

Natural polishing of the fossil Collision marks with pebbles

• Fossil trunks were transported as clasts among high energy river bed load and deposited in the river terrace

• Thus, fossil trunks are older than the fluvial terrace, with na estimated age between 15 to 5 million years old.

These trees share the features of the same tree attributed to Annonoxylon teixeirae, whose present best known representative is the Annona-Tree

Where can you find Annona-trees in the wild forests nowdays?

In which type of climate?

Present distribution of Annonaceans

Hot and humid latitudes

Paleoenvironment of Naturtejo Geopark 15-5 million years ago

Hot and in some periods more humid climate