For an ever-so-slightly delayed (cough) blog update we’re off to the beautiful Yorkshire Dales, or to be precise, the wonderfully named Norber.
Norber is a classic type locality for a glacial erratic, a piece of rock that is different from those surrounding it due to having been transported by ice. Here, boulders of cross-bedded Silurian greywacke perch on pedestals of Carboniferous limestone after being plucked from the valley floor and and being transported both downstream and up the sides of the valley by glacial action.
Time to draw your attention to another fantastic video from MinuteEarth, this time on greenhouse gases. Now we’re all familiar on the rough school-level science of acting as insulation for the planet but if, like me, you weren’t exactly sure how this happens, here’s a little refresher:
Many of us are familiar with making small-scale macro and micro geological observations on field trips and in labs, peering curiously (we hope) at bedding planes, grain boundaries, fossils and outcrop structure. However, it is equally as important to take a step back and consider how these minute details impact on the landscape and topography around us. Here in Britain, we are lucky to have incredibly diverse geology in a relatively small area, and these large scale mega observations* can prove pretty valuable in plotting out large scale features, such as major fault lines and distinct changes in rock type or structure.
Along with old-school paper maps, this is where Google Earth really comes into its element. Being able to see aerial imagery along with elevation and alternative viewing angles means you really can explore the world from your desk (or even sofa). So, carrying on the theme of the exotic, we’re off to Hull. Continue reading →
Last weekend I decided to spread my wings, or boot-laces, and escape from the Vale of York to pastures new. Just for the day though, let’s not be too rash. We headed on the slow train out of York to Hebden Bridge, which took about an hour and a half and was definitely one of the more pleasant journeys I’ve had with Northern Rail.
Geologically speaking, the train line marks out a good transect of Late Palaeozoic and Early Mesozoic palaeoenvironments. In the Vale of York, Permian sandstones, siltstones and muds from lakes and lagoons are often overlain by thick Quaternary clays, sands and gravels, again laid down by lakes and rivers at the turn of the last glaciation. Where the bedrock is closer to the surface, the ploughed fields are stained red from the vibrant iron oxides in the rock.
For a brief overview, here’s a screencap from the marvellous BGS Geology of Britain Viewer:
For today’s installment we’re flying off to Iceland once more, and to Seyðisfjörður in the east of the country. It also manages to capture the famous saying of ‘the land of fire and ice’ pretty well, with snow lying immediately on top of numerous repeated lava flows. (This photo was taken in July too – it’s quite nippy this far north!) We geologists always need a scale in our photos, so if you have a look at the electricity pylon at the bottom right you get a good idea of the scale of this scarp! We also love a bit of differential weathering, and I love how the stream has zig-zagged its way down each individual lava flow, always after the path of least resistance – I’m sure we can all relate sometimes!
The principle of uniformitarianism, neatly summed up by the enterprising geologist James Hutton as “the present is the key to the past”, is one of the key geological laws drilled into many fresh-faced earth science students. Put simply, it means that by looking at the systems and processes that operate upon and within the earth in the modern day, valuable insight can be gained about the past history of our planet.
This principle can also be extrapolated into the future. By looking at historical events, scientists and geologists alike can use existing evidence and data to form models and prediction of how similar events could affect the earth today.
April 2015 marks the 200th anniversary of the Tambora eruption in Indonesia, the largest volcanic eruption in modern human history. Despite being essentially on the other side of the world, the Tambora eruption had a global impact. Far from the heavy fall of ash that coated many of the neighbouring islands for days, the colossal mushroom cloud of sulphuric aerosols quickly circumnavigated the earth’s atmosphere, blocking the sun’s rays and significantly altering existing climatic systems.
Obligatory Google map pointer
Fast-forward 195 years and we arrive at a volcanic event that nearly everyone here in the UK can recall, mostly for the funny sounding name and some significant inconveniences in air travel. Before Eyjafjallajokull blew its top, most people in the UK and northern Europe regarded volcanoes as a distant hazard, something that would be seen on news bulletins but not have a direct impact. It was a gentle reminder that the processes that built this earth are still happening today, despite our increasingly disconnected relationship with the outside world. In a developed and modern society, it can appear that natural disasters only happen “somewhere else”, but the atmospheric circulation that distributes volcanic ash and gases all over globe ensures that “somewhere else” can rapidly develop into “everybody’s problem”. Continue reading →
As we all know, I’m a sucker for a good documentary, even those that aren’t related to geology.
However, this time around the subject couldn’t be more relevant; falling prices, conflicts in the Middle East, debates about sustainability and the implications of fracking all mean that oil is the hot topic du jour.
In a three-part series, professor Iain Stewart explores the history of our global addiction and reliance on oil, and how it has altered economics, politics and our environment in a timespan little over that of a human lifetime.
Here is yet another Icelandic photo, and probably of one of the more photographed expanses of cliff on the island (maybe in the world?) However, this one has me baffled!
Now, we can all see the columnar jointing in the basalt, and there is clearly a relationship between it and the large, dark section at the centre of the outcrop. The thing that stumps me is what the relationship could be between the basalt and the blob (I promise I can be more eloquent sometimes!
If anyone could help me out, I would be much obliged!
Carrying on with Friday’s theme of rooting through old photos, I thought I’d share a few from a family trip to the Scilly Isles way back in 2008.
Aerial view from the incoming helicopter
I mentioned in a previous post the great Cornubian Batholith, an enormous granite body that makes many appearances across the south-west of England. The granite was emplaced during the Late Permian, as part of the later stages of the Variscan Orogeny. As well as the many tors of Devon and Cornwall, one of these outcrops is the characteristic archipelago of the Scilly Isles, a scattering of islands clustered beyond Land’s End. Up until around 500 AD (a mere blink of an eye from a geologist’s perspective), the islands were one large outcrop, before rising sea levels split it into around fifty-five separate islands and islets.
Out of these fifty-five, only five of the islands are currently inhabited: St Mary’s, St Agnes, St Martin’s, Bryher and Tresco. At extreme low tides it is also possible to walk (or at least paddle!) between some of the islands, and the relatively recent sea level rise means that ancient field boundaries are also exposed by the receding water. From above, the Scilly Isles look like a tropical paradise, with their isolated white sand beaches. At times you could be forgiven for the mistake, as the westerly position of the archipelago means that they are exposed to the warming effects of the Gulf Stream. However, it is far more likely that it is due to the high quartz content of the eroding granite!
Now, these photos are from a looong time ago, so apologies for the rather dodgy nature, but I thought I’d provide a quick overview of my time in paradise!
Incoming swell at the appropriately named Hell Bay
Written In Rock 