145 million year old fossil cypress forest along the English coast

The Petrified Forest of Dorset is a stretch of coastal southern England dotted with limestone mounds containing the remains of late Jurassic cypress trees.

The fossil forest consists of 145 million-year-old tree stumps that died on the Dorset coast during the Jurassic period, 145 to 201 million years ago, and stretches for 93 miles. The area contains some of the strangest fossils, caused by colonies of tiny algae-like bacteria that colonized the trees shortly after they died. Over time, the bacteria trapped and coagulated calcium carbonate grains on the trees, forming a living limestone mat called thrombolite that can still be seen today, Live Science reported on December 6.

Fossil tree stumps in a forest in Dorset. (Photo: Alamy).

The forest developed during the late Jurassic period, at a time called the Jurassic-Cretaceous boundary . During that time, temperatures dropped and sea levels fell, exposing new land and forming coastal plains where life, including trees, could thrive. Conifers, ferns, and cycads grew on what is now the coast of England as the ocean receded. Flowering plants had not yet evolved at this stage in Earth's history, but dinosaurs may have roamed the forest, according to the Wessex Coastal Geology page by Ian West, a geologist and visiting scientist at the University of Southampton in England.

The forest was short-lived, as sea levels quickly rose again, submerging the trees in saltwater. Instead of rotting, the roots and trunks were preserved by bacteria. Eventually, the trunks broke off, leaving round mounds that remain on the shore, forming the fossil forest.

The mounds of algae in the fossil forest are located near cliffs overlooking the English Channel. Most of the tree remains inside the mounds belong to an ancient species of cypress called Protocupressinoxylon . As such, the forest provides important information about the ancient environments in which dinosaurs lived during the Late Jurassic period.