Knock on wood, touch wood

Evidence of the world’s oldest rainforest was discovered in the underground workings of a coalmine in Illinois, US. It is 300 million years old, from the Carboniferous period, when the world’s best coal resources were formed.

• Trees first began to cover the Earth’s surface some 380 million years ago, 140 million years before the first dinosaurs appeared.
• The oldest tree fossils ever discovered on Earth were found near New York State’s Catskill Mountains. It is 385 million years old and is the remains of a fern-like plant that formed the Earth’s first known forests.

The largest petrified forest in the world is in Lesvos Island, Greece. The second largest is Arizona’s Petrified Forest.The Petrified Forest in Arizona became a national monument in 1906. Its fossilized trees give us a glimpse into earth’s ancient past. How?

During the petrification process, ground water carried dissolved minerals into logs buried by sediment, forming quartz crystals which filled hollows and cells—a process so exact the resulting fossils show many details of the original living trees. Traces of iron and other minerals combined with quartz often creating a brilliant rainbow of colors.