Edinburgh recently held a volcanology conference (VMSG), which is quite fitting seen as an ancient volcanic complex can be found at the centre of Edinburgh! The following photos are just a few photos from a trip up Arthur’s seat whilst at VMSG…
Another stop on the trip to Scotland involved looking at the oil shale’s exposed beneath the Forth Road Bridge.
Unfortunately the tide was in meaning we couldn’t look at the outcrops we had intended to, but we did get to see some of the sand produced from these rocks.
If you take some of this black sand and heat it up (we used a candle), it is possible to release the hydrocarbons in the rock. Nothing particularly scientific, but its a fun experiment to determine if the rock contains abundant hydrocarbons!
In Geology an unconformity is a surface separating two rock types of different ages from one another. An unconformity represents a period of erosion or non-deposition in the sedimentary record, i.e. a gap or hiatus where we have no record of what happened.
One such unconformity is Hutton’s Unconformity. The confusing part is that the name Hutton’s Unconformity is the name given to several unconformities identified by the famous 18th century Scottish geologist James Hutton. On a recent fieldtrip to Scotland we visited Hutton’s Unconformity at Siccar Point, but other unconformities identified by James Hutton can be found on Arran and near Jedburgh.
When sediments (fragments of previous rocks) are deposited (settle before becoming a rock) they form layers of progressively younger material burying the older material. If a sedimentary rock is the correct way up the further up the rock you go the younger (closest to present day) it is.
At Siccar point we can see two distinct units rock, with the layers of rock (bedding or strata) in the upper and lower units being at different orientations from one another. This means that before the second (upper) unit was deposited the lower (older) unit was tilted and eroded, producing a gap in the geological record.
Unconformities are crucial to our current understanding of geology. They paved the way for us to consider deep time, that is essentially an appreciation of the fact it has taken a very long, yet quantifiable length of time for the rocks we observe around us to have reached their current situation. For the rocks here at Siccar point that means; deposition of the older sediments, tilting of the older sediments, erosion, then the deposition of the younger sediments on top. This order of processes cannot possibly happen quickly!
Unconformities have also been used as evidence that the mechanisms governing the production of these rocks (and the universe) have, and always will operate in an assumption known as uniformitarianism. Uniformitarianism is a counter (and more accepted view) than the opposing catastrophism, which implies that the Earth was created in a series of sudden short lived events.
I had pretty much forgotten about this amongst everything else but I still think this is worth posting. On the way back from doing Dream of White Horses on Gogarth (2 weeks ago) we decided to have a quick stop on the beach and found some interesting geology to look at. From just a few simple observations on this beach some really key geological principles can be demonstrated.
An intrusion is when molten rock is injected into another rock and the word ‘mafic‘ refers to the composition of the intrusion. Here I am using mafic to describe an igneous rock which is dark coloured and with crystals too small to identify, but its actual definition is a silicate mineral (contains the elements silicon and oxygen) which is rich in the elements magnesium and iron. A metamorphic rock is a rock which was previously another type of rock which has been physically/chemically altered through increased pressure and temperatures in the Earth.
This simple observation of the dykes on this beach also demonstrates a crucial geological principle, so called ‘cross-cutting relationships‘. The principle of cross-cutting relationships states that the geologic feature which cuts another geological feature is the younger of the two features. Geologists use observations like this to build up the sequence of events (relative ages as opposed to absolute ages) that led to the particular setup which we observe. From this we can reliably say (with no need for dating techniques!) that the dykes here are younger than the metamorphic rocks they intrude. This concept of relative dating was noted as early on as 1795 when James Hutton published his ‘Theory of the Earth‘, and is not just limited to intrusions, it can be applied to a whole array of geological features such as faults or erosional surfaces.
I would imagine most of the beaches this side of Anglesey have things of interest. If you find yourself passing by might be worth a quick look 😉
Whilst on holiday in Finland last year we visited an Island not far from the centre of Helsinki and found some interesting things to look at…
The linear features here are called striations and have been gouged into this rock. They are caused by the movement of a glacier over the bedrock, through the process of abrasion. Abrasion is a term used to describe when fragments of rock captured by a moving glacier are pressed onto the surface of the underlying rock. As the glacier drags these rock fragments along lines are scraped into the rock. Striations are a common feature of glaciated landscapes and are just one of many features glaciers can produce.
Striations such as these along with other glacial landforms can help us to reconstruct the dynamics of past glaciers, and help us understand more about modern glaciers. The presence of glacial landforms where we no longer have glaciers (such as here in Helsinki) demonstrates how the environment can change over time.
If you find glacial landscapes interesting you may find Rock Paper Glacier! blog to be of interest.
This example near Helskinki really does show us that even in built up areas we can still observe the influence of the forces that shaped the landscape around us!
Before heading off to North Wales last week I went to Trowbarrow quarry in Lancashire for a quick climb and poke about but haven’t had time to post about it.
This disused quarry is a geological SSSI with lots of high quality (and some crap!) climbing on offer. One of the most prominent geological features at Trowbarrow is the near vertical nature of the bedding planes. We can see this on the photo of the main wall where the routes follow cracks along the bedding. Other interesting geological features at Trowbarrow worth seeking out include; faults, folds, fossils and apparent paleo-karst.
The photo of the main wall above is actually one from a few years ago but it hasn’t changed much, except some people say that the entire right hand side of the main wall is rotating causing the cracks to widen? The climbs on the righthand side of the main wall are looking a little ‘unstable’ but I’m sure people can make their own judgements about whether to climb them…
Like many of the climbs at Trowbarrow Coral Sea (photo above) follows the bedding plane, and as the name would suggest numerous fossils are observable all the way up.
Another feature at Trowbarrow is Fluting. This is a common feature on limestone and is caused by differential weathering and erosion. It can be observed at Trowbarrow at the top of Assagai wall, where it forms the spectacular finish to Assagai (good sling runner in the flutes!).
In terms of the climbing the obvious mid grade classics Jean Jeanie(VS 4c), Coral Sea (VS 4c) and Assagai (HVS 5a) are certainly worth a look. Polish can be a bit of a problem at Trowbarrow (especially on Jean Jeanie!) but generally the climbing is really good quality!
Apologies for the multiple posts today but there’s lots to post about since returning from Wales!
I hadn’t climbed on Lower Pen Trwyn (LPT) before but would certainly go back. In terms of the Climbing LPT has some really good routes across the grades and has the feel of sport climbing elsewhere in Europe, especially if the sun is out! Could The Orme be the Welsh answer to Kalymnos?
The approach is pretty simple (steep start) with some good geology to maintain interest on the way in. The following photos and thoughts are by no means an exhaustive study, and were captured in a passing by type manner with the intention of inspiring climbers to look around them on the way in to LPT.
Presumably the sediments above the limestone are relatively recent, and are sourced from the limestone above on the Orme? This short transportation distance however does surely not provide a satisfactory explanation as to why there is such rapid variation observable in roundness and sorting between beds?
Climbing wise Under the Boardwalk stands out as a real classic of the crag, proving to be a tricky little number requiring a sustained effort right till the end, but the crag contains abundant quality climbs. At the far right end there are several ‘easier’ sport routes in the F6a(ish) range with Beauty is Only and Skin Game being good fun.
Oh and remember that LPT is tidal, and accessible apart from about three hours either side of high tide. Its also worth noting that the 1st bolt on most climbs is pretty high (due to the tides).