The region of the Mining Complex of Pejão is part of the coal basin of the Douro. This coal mine has a length of about 50 km, constituting the most extensive continental carboniferous outcrop in Portugal. Here is a vast fossil heritage, highlighting the plant fossils from the carbon period of the Paleozoic era, between 245 and 359 million years ago. Here we can observe a precious collection, owned by António Patrão, which includes a large number of fossils in excellent condition. The collection of fossils by the hands of this old miner began in the time that he worked in the mining complex, and continues to the present day. His curiosity led him to gather a collection of inestimable value allowing us to understand a little better this time in Earth’s history.
These magnificent fossils transport us back in time, going back over 300 million years, when the whole mass of the planet was concentrated in a single supercontinent: the Pangaea. During this period, this territory was located near the equator and was covered by dense tropical forests with numerous ponds, the result of a hot, humid climate and oxygen levels in the atmosphere far above of those currently registered. At this point, the fauna of these forests was dominated by amphibians, reptiles and large invertebrates, with dragonflies to reach 75 cm of wingspan. As the fossils collected allow us to observe, the vegetation was different: at a time when there were no flowering plants, ferns dominated as the lepidodendron, the calamites and other ferns, and had already emerged the first gymnosperms. Highlighting the calamites, very similar to contemporary horsetails but at the time, struck tree size, exceeding 30 meters. These were leafy forests with very high amounts of organic matter which have undergone, over time, sedimentation processes, subjected to low oxygen conditions and high pressures and temperatures, giving rise to the current coal mines, such as the exploited for decades in the Mining Complex of Pejão.
