Nibong Wood Fossil Borneo.
Ancient wood fossils found in Penrissen point to past volcanic activity.
THE discovery of a wide variety of wood fossils aged between two and 12 million years in Penrissen is seen to be evidence that the area near Kuching was once active with volcanic eruptions.
The fossils are also proof that Borneo, Sumatra and peninsular Malaysia were once linked to each other.
Sarawak Museum Department curator of natural history Dr Charles Leh said that tectonic movements had moved the land masses apart.
“Borneo is relatively stable today because it has moved away from the volcanic zones in Sumatra, which is still very active. The evidence shows that Borneo, at one time, was next to peninsular Malaysia and you could have walked from Borneo to the peninsula,’’ he told The Star.
Dr Leh explained why Borneo, peninsular Malaysia and South Asia had similar plant species and animals like the tiger and tapir, although these animals had become extinct in Borneo.
He said the discovery of fossils of oak trees, nibong-like palms and pines in southern and central Sarawak proved the existence of rich flora in Borneo millions of years ago.
Some species of oak trees and nibong-like palms are still found in the Penrissen, Baram and Balleh areas.
He said the wood fossils were proof that Malaysia was among the world’s 12 mega-biodiversity hot spots. On how the wood fossils were formed, Dr Leh said the forest could have been fossilised during volcanic eruptions.
“Volcanic ash and mud flows may have entombed the trees as they had been transported down some distances from their site of growth. The trees began fossilising when climate conditions changed, covering them with mud, sand and volcanic ash before they rotted.
“Water which seeped through the mud and sand into the buried logs then filled the empty cells of the decaying wood with minerals,’’ he said.
After millions of years, the wood was gone but rocks and minerals were in its place. However, some fossil woods retained their original structure, he said.
From the collection of wood fossils, it could be concluded that the number of plant species had increased substantially over time and the different types of plants characterised different geological periods, he added.
“Because of the evidence, we now have new knowledge of our geological history. The fossil history of wood in Sarawak and Borneo is little known and not documented,’’ said Dr Leh.
Sarawak Museum is inviting researchers to study Sarawak’s fossil plants and do DNA tests.
Dr Leh said that Sarawak had the largest collection of wood fossils in South-East Asia and exhibits from a private collector were now on display at the museum’s Natural History Fossil Wood Gallery.
More than 300 pieces of the fossils in the collection originated from southern and central Sarawak.
Fossils from the southern region were harder, indicating they were older. Those from central Sarawak were younger and more crystalline in nature.
Sarawak Museum.
