What's on offer at Bells Rocky Tours?

This front page has items of current geological interest, and pointers to other site pages
There are courses to support OU Earth Science study and of more general geological interest in 'Courses'
Look at 'Reading the Rocks' to understand more about field observations and techniques
Try 'Geovideos' to see some of my earlier OU work
'Georambles' are downloadable mini-guide books for individual days with a geological theme.

Hope you find something of interest. If you'd like me to add anything or would like to book a tailor-made course, please get in touch.

...and another earthquake in Northern England

Surprisingly, and unusually, we've had another large (for us) earthquake in northern England only days after the last.

This new earthquake occurred at 9.03pm on Monday 3rd January 2011. Its originated at 6.2 kms depth, epicentre lay some 9 km north west of Ripon in north Yorkshire. It registered 3.2 in magnitude (no longer 'on the Richter Scale' but using a roughly comparable measure), which is slightly smaller than the Coniston earthquake before Christmas.

Are the two earthquakes related?

Unlikely. Both probably represent reactivation of old fault lines that once formed part of active deformation in Britain but have been 'inactive' for millions of years. (Arguably, they must be 'active' fro earthquakes to occur along them, but it's important not to confuse this term with faults that are currently part of the system that allows continents to move relative to one another.)

Why these old faults should accommodate present-day crustal movement is a matter of speculation. True, Britain is part of the plate tectonic regime - all the Earth's crust is. And true, Britain lies close to the eastern passive margin of the still-spreading North Atlantic ocean. It may be that these two earthquakes are linked to this movement. However, I still suspect that vertical uplift caused by the adjustment of this part of the crust to the removal (by melting) of an ice sheet many hundreds of metres thick only some 10,000 years ago is a more likely cause.

Remember, ten thousand years is virtually nothing in geological time.

Will there be more?

Yes, and no! If by this we mean are these two earthquakes part of a predictable series that is on-going, then no. But if we mean will tectonic processes - either plate movement or isostatic rebound caused by ice melt continue and cause further earthquakes in the future, then undoubtedly yes.

We're lucky though - our part of the crust is very, very unlikely to experience a severe earthquake (one that causes major damage and loss of life) in the humanly foreseeable future. Count your blessings!

Wow! An earthquake in the Lake District

Just before Christmas - actually at around eleven pm on 21st December 2010 - a rare event occurred. There was an earthquake in the Lake District.

I was in Penrith, but felt nothing, and indeed didn't get to know anything about it until I listened to the midnight news. But according to the BBC blog, there were distictly noticeable effects - rattling Christmas cards and even loosened tiles - in Kendal and Barrow, SW Scotland , Isle of Man and it was felt even as far away as Gateshead and the English Midlands.

According to BGS, the earthquake had a magnitude of 3.6 Remember, this is a logarithmic scale, and each integer increase represents about a 30-times actual increase in intensity,so it's just about 1/30,000th the force of the major earthquake in Chile this year which was around 8.8. Enough strength to do minor damage, not enough to do major harm, as in Chile.

We're lucky in Britain, since we live in a tectonically quiet area. Earthquakes as big as this one happen about once a year over the whole of Britain - much less frequently in any specific county.

The epicentre (the point on the surface directly above the earthquake) was sited at Coniston, so why did one occur here?

Coniston lies astride a major fault that tracks right through the Lake District, but which has long been 'inactive' (probably since Permian times, 250 million years ago). It might not have been that fault that moved, I certainly will never know. Why should any fault move here? My guess is the effects of continuing isostatic rebound - the adjustment of the crust locally to the removal of the ice load at the end of the last Ice Age some 10,000 years ago.

Slow stuff, isn't it?

Snails and Fossils

You might have seen recently that an amateur scientists has researched whether garden snails have a homing instinct, and found that they can find their way home over a distance of some 30 metres.

It's set me off thinking that there's lots we don't yet know about fossils and how they really lived.

One of the most tantalising mysteries is colour, since we rarely (ever?) find any evidence for what colour fossilised creatures were. But if our current ecosystems are clues to past ones, many life forms will have used colour as camouflage, to establish territories, attract mates and to warn off predators.

We also can only speculate whether animals could navigate or had a homing instinct. We know generally about the geographical range of many species in the past, but I for one have always assumed these were controlled by climate or temperature or some physical constraint, rather than biological instincts of the creatures themselves.

We've a lot to learn about the fossil world.

Merapi erupts again

Late October has seen yet another eruption of one of the most active volcanoes in Indonesia - Merapi. According to John Seach (volcanolive.com), Merapi has produced more pyroclastic flows than any other volcano in the world, and has been active for at least 10,000 years.

It's very sad that almost every eruption of this and other volcanoes, particularly outside Europe and USA, leads to loss of life. Predicting when volcanoes are going to erupt is high on the 'to do' list for geoscientists.

However, three aspects of this eruption particularly interest me...