Here we have a photo from a fieldtrip way back in 2012 to Cornwall, the most southwesterly county in England. This is taken from the viewing platform at the Wheal Martyn china clay mine with some atmospheric fog and mist as a free gift (the fog didn’t actually lift for the whole week we were in Cornwall, so we never got a half decent view of one of the most beautiful areas of Britain).
For a special treat I’m delivering a winning combo of a Throwback Thursday and a Photo Friday, and today’s exotic location is the Isle of Arran, on the west coast of bonnie Scotland (not to be confused with the Aran Isles off the coast of Ireland).
Arran is a bit of a Mecca for geologists, as it has an enormous variety of lithologies and geological processes packed into a relatively small area (it’s about an hour’s drive top to bottom).
I first encountered Arran’s geology way back in 2010, being the destination for my AS and A-Level geology field course (for non-UK readers this is age 16-18).
It goes without saying that Arran is one of the best field locations to study the law of cross-cutting relationships, as there are numerous outcrops illustrating the relationship between the metamorphic, sedimentary and igneous chapters in Arran’s history.
I stumbled across this video the other day, and it’s absolutely brilliant! I’m a bit of a sucker for slick animation, but I think this sums up the past 4.6 billion years pretty conclusively.
So this morning Twitter dutifully informed me that it was World Soil Day, so here’s a slightly soil-related Photo Friday. Admittedly, this is a terrible photo (I’m blaming the combination of French midday sun and the shade of a whopping great forest), but let’s carry on regardless.
I thought that this photo illustrated fairly well the way that geologist rely on soil to map the underlying rock units in areas where there aren’t particularly good exposures or outcrops. However, here you can see a clear difference between the red oxidised sandy soil at the top right of the photo and the muddy greyish soil near the edge of the road. Having such an extreme variation in soil types in such a short distance (in this case a matter of a metre or so) rings alarm bells for us geologists, and indicates that the contact between two different lithologies is nearby, even if it may be completely obscured.
I’ve just finished watching the fantastic Iain Stewart in an old Horizon episode about the Chelyabinsk meteorite that exploded above Russia last February. For anyone interested in the wider role of space objects in Earth’s history, this is a must-watch. Get there quick though, as expires on iPlayer at 9pm tomorrow, and unfortunately is only available in the UK (a shame, as other channels can learn a lot from the presentation of BBC documentaries!!)
Written In Rock 