Crater holds Earth clues

Geologists at Imperial College, London are to lead an international effort by scientists to discover the shape and structure of the largest known crater on Earth.

The Chicxulub crater, in Mexico is thought to have resulted from an impact with an asteroid or comet 65 million years ago. Many scientists have suggested that there may be a direct link between the impact and the extinction of the dinosaurs, flying reptiles, giant marine reptiles and other animals and plants which occurred at about the same time.

Joanna Morgan of Imperial's department of geology says a detailed study of the shape, structure and extent of the crater will result in a better understanding of the process of crater formation and modification during large impacts and enable scientists to quantify the environmental impacts of such craters.

Asteroids impact could have led to big changes to global climate and this could account for mass extinction at the time. An understanding of the causes and consequences of mass extinctions and determining whether they are the consequences of some external catastrophic agency or of the natural progression of evolution is of fundamental importance in geology and the life sciences.

Modelling the environmental changes and Earth's apparent rapid recovery is also important for climatic modelling - for example in studying global warming. A key part of the work will be a seismic analysis of the Chicxulub. This will give an image of the crater down to 30 kilometres.

The work could also provide insights into the main processes to have shaped the surfaces of Mercury, Mars and the Moon. Dr Morgan says: "Although we can observe craters on the inner planets and their satellites we actually know very little about their formation." There are few examples of very large craters on Earth and after Chicxulub, estimated to have a diameter of between 170km and 300km, the next two biggest are eroded and deformed. "Chicxulub offers a unique chance for us to study the crater mechanism."

The project will involve researchers at Imperial working with scientists in Mexico, the United States and Canada.