A big hole in the ground

It is hard to get a grip on just how big the Grand Canyon actually is.  446km long, up to 29km wide and 1,800 metres deep make for a big hole.  The geology of the canyon is as spectacular as the view but its formation has been the subject of a lot of debate.  It is quite obvious that it has been formed by erosion from the Colorado River, but the rate of erosion has been the topic of much geological debate.  The most recent interpretation of the erosion is that although parts of the canyon formed up to 70 million years ago the whole drainage path of the Colorado developed through the length of the Canyon in the last 6 million years.

Half the UK

The investigation into shale gas continues with an intial assessment of the potential of Britain's geology for shale gas exploitation.  A report produced for the Department of Energy and Climate Change estimates that up to half of the UK could have suitable geology.  This isn't too much of a surprise, as shale is the most common sedimentary rock and hasn't featured as a strategiec resource for the country in the past.

The resource is there, the question remains whether the economics, energy security and environmental demands can all be made to balance.  What do you think?

Dogger

 

A dogger is a concretion, a mass of sedimentary rock that has been cemented more than the surrounding rock.  These often weather out of their original rock, the most spectacular examples in the UK are those in Laig Bay on the Isle of Eigg (shown above).  The Moeraki Boulders on the South Island of New Zealand are another example of this feature.

The name was also used as a term, though now superseded, for the Middle Jurassic.