at centre of Patagonia, at Sarmiento and Jaramillo, there are two woods in near regions...
They are called "wood", because their trees weren`t dragged along by rivers or glaciers, as it happened at other places in the world.. so, they have unique characteristics.
At the beginning of the Tertiary Era , the Andes Range arose and thus, prevented the Pacific ocean`s humidity from passing, producing eruptions. The ash and lava`s deposits spread allowing
a slow process of transformation of these trunks into stone.. it is hard to imagine that this arid place was a fertile region, with woods and lagoons, inhabited by a varied fauna, which rests were found fossilized, as well.