MADAM - As a trained geophysicist with experience of working on site with hydraulic fracturing, I feel that many of the points raised in a recent article (Anti-fracking activists from Stroud join protests in Balcombe, SNJ 21/8/13) are shockingly wide of the mark, and are in desperate need of rebutting.

The '30 signatures' collected by James Beecher and his family on a 'cardboard sign' amount to nothing more than a bit of Stroudie fun.

Nor should they.

It is inconceivable that fracking should ever take place in Stroud (or indeed Gloucestershire) since the Jurassic-aged local limestones and clay preclude shale gas reservoirs.

Any claims to the contrary demonstrate wilful ignorance.

A similarly unhelpful tendency to scaremongering is encapsulated in asserting that fracking is 'globally dangerous'.

What a sweeping statement!

First, based on our understanding of the mechanical strength of shale and case studies of fracking operations in the USA, it is extremely unlikely that seismic events induced by fracking will ever reach a magnitude greater than three.

These are likely to be detectable by few people and are highly unlikely to cause any structural damage at the surface.

Secondly, most aquifers used for drinking water in the UK lie within the first 300 metres below the surface, while fracking operations would take place at a depth of more than two kilometres.

Concerns over groundwater pollution are very often overstated in the media.

Shale gas can be extracted safely by hydraulic fracturing, provided that best practice is rigorously applied.

The technology to explore for and to extract shale gas has been established for over 50 years.

If shale gas usage were to substitute for the burning coal, there would be a potentially beneficial reduction in CO2 emissions as we move to a low carbon economy.

Most of us are fully aware of a pressing need to reduce our dependence on fossil fuels.

I sometimes wish that protesters like James Beecher and others at Balcombe would join the intelligent debate rather than resorting to background histrionics, which benefit no-one, and often have the opposite effects to those intended.

Jonathan Paul FGS Department of Earth Sciences University of Cambridge