I read with interest the article about Nigel Taylor's concerns about the Mendip volcano. I can re-assure people in Mendip that there is no danger.

Over 350 millions years ago the rocks of the Mendips were part of a warm shallow sea near the Equator and there were a number of small volcanoes around. The public can see examples of this dark volcanic rock on the shore near the old pier in Weston-super-Mare and at Middle Hope near Sand Bay.

I am sure everyone in the Mendips will have also found fossil shells, corals and sponges in the limestones making up most of the Mendips that provide the evidence of these ancient times.

Even before the dinosaurs ruled the Earth the Mendips had moved from the Equator to the north by the movements of the Earth's tectonic plates. The limestones were then pushed into a huge Himalayan scale chain of mountains stretching from Britain to the Middle East by the collision of the African and European continents.

The tilted rock layers in Cheddar gorge attest to these huge earth movements that happened tens of millions of years after the Mendip volcanoes had become extinct. The huge mountains were then eroded and their remnants now form the beautiful rolling landscape of Somerset and the Mendips.

Simple observations of marine fossils in rocks at the tops of hills and mountains and tilted beds of sedimentary rock are what led people like William Smith, the great Bath engineer and father of geology, and Charles Darwin to conclude that the history of our planet is incredibly long.

Nigel Taylor also raises the issue of fracking to release natural gas from rocks. There is no doubt that the new technology of breaking up rocks full of natural gas has environmental issues which need to be addressed. However there are also no human activities that are truly free of risks and society will have to weigh up the costs, including harm to the environment, against the benefits of a major source of energy for the UK to keep the lights on.

There needs to be assessment of the risks of fracking independently from the energy companies. That is indeed one reason why the tax payer supports academics like me and scientists in government agencies to provide independent and impartial views.

However, all assessments have to be based on sound science and so scare stories with no basis are not helpful in what are serious issues of energy supplies and the environment.

Steve Sparks

Professor of Geology

University of Bristol