Friday, 7 February 2014

Ancient Volcanoes and Fossilised Animals

Pompeii victims (courtesy of the BBC)
Now you all probably recognise the picture above. In 79AD, Mount Vesuvius erupted, wiping out the city of Pompeii, killing and burying its residents under a dense layer of ash. Scientists now believe that similar events may have occurred 130-120 million years ago, instantly killing the animals of the area and preserving them in a similar way. Fossils beds from the Liaoning province in NE China are the site of some exceptionally well preserved feathered dinosaurs, mammals, lizards, birds, fish and insects. They would have lived in an area that was surrounded by volcanoes, and would have been the victims of pyroclastic flows (I'll explain them in a minute) that spread out across the landscape. Like the people of Pompeii, they would have been killed instantly, before being buried under the ash, allowing them to be preserved in mid-movement. The animals were found together as their carcasses would have been transported by the flow and deposited in the same area.

Fossil dinosaur and birds (courtesy of the BBC)
Pyroclastic flows consist of hot, dry rocks and hot gasses that travel away from a volcano after an eruption. The coarse rocks move along the ground, and a turbulent cloud of ash rises above them, which combined can destroy nearly anything. Flows can reach speeds of over 50 miles per hour and temperatures often range from 200-700 degrees centigrade. The rocks batter, destroy or carry away most objects and structures, whilst the temperatures burn things like vegetation and houses. Sites are then buried by the hot rocks and ash. So basically, you do not want to get in the way of one of these things!

Although that's all very doom and gloomy, these ancient eruptions have allowed us to have these exceptionally well preserved fossils, giving palaeontologists a greater understanding of life and evolution from such a long time ago.

No comments:

Post a Comment