These petrified fossils are from the National Fossil Wood Park in Thiruvakkarai, Tamil Nadu. The fossils at National Fossil Wood Park were first unearthed by M.Sonneret, a European naturalist in 1781, and consequently by the Geological Survey of India. The fossilized tree trunks, which are 20 million years old, are brown and have the appearance of wood but are actually as tough as rock. Over time, the organic matter inside them, got replaced by silica and they got fossilized.  In technical terms it’s the Mio-Pliocene Sedimentary rocks. These rocks here are called Cuddalore sandstone formations. Scientists conjecture that the trees did not originally grow here but were transported to the site before they were petrified. About 20 million years ago, these tree trunks are believed to carry by rivers and deposited in the water bodies along with sediments. In the absence of roots, barks and branches it make certain that these tree trunks are transported to the present location and fossilized.


Petrification is the process of turning living organic material into stone. This process takes place when the molecules in an organism are replaced with the molecules of a mineral. A petrified fossil is different from other fossils such as resin fossils or permineralized fossils because the original material of the organism is still intact in resin fossils or permineralized fossils. Petrification happens when a living organism, such as a tree, gets knocked down and buried under sand and mud during a flood. The buried tree is cut off from oxygen, which prevents bacteria from rotting away the wood. Over time, water that contains a lot of sediment and minerals enter the pores of the tree. Eventually the water evaporates and crystals from the minerals are left behind in the tree. These minerals then start to replace the carbon compounds in the wood. Eventually all of the wood is replaced by minerals. This process can sometimes take between a few years to millions of years. Calcite, iron, silica and copper are some of the most common minerals found in petrified fossils, although many types of minerals can petrify fossils. Petrified wood is the most common type of petrified fossil, but all living organisms can be petrified. One of the most common types of petrified animal fossil is petrified bone and teeth. Dinosaur bones are sometimes petrified after being buried for millions of years after mudslides and floods. These types of petrified fossil are less common than petrified wood because bone is more fragile and easily damaged by water and ice.


Paleontology is the study of ancient life, from dinosaurs to prehistoric plants, mammals, fish, insects, fungi, and even microbes. Fossil evidence reveals how organisms changed over time and what our planet was like long ago. The term itself originates from Greek, palaios, i.e. “old, ancient”, ontos i.e. “being, creature” and, logos, i.e. “speech, thought, study”. Paleontology lies on the border between biology and geology, but differs from archaeology. Paleontology incorporates knowledge from biology, geology, ecology, anthropology, archaeology, biochemistry, mathematics, engineering and even computer science to understand the processes that have led to the origination and eventual destruction of the different types of organisms since life arose.