Monday, 25 July 2016

Earth and Marine Science Summer School

Hello all,
As I reminded you, I recently attended an Earth and Marine science summer school in Southampton. We were based at the NOC (National Oceanography Centre) and partook in different activities.

Day 1
This was not, strictly speaking, day one because we had arrived the day before, but this was our first proper day at Southampton. The Earth science section went to Lulworth Cove, the other side of Bournemouth, and I was on this side.

Lulworth cove is a fantastic place, with fascinating geology. The rocks at Lulworth Cove tell a story. The oldest rocks there are Portland Stones, which is a limestone and formed 150mya in water at a depth of 50-100m. This is because calcium carbonate dissolves in deeper waters. Portland Stone is dark and quite hard.

Then, you have the Purbeck bed, with clays and limestones. This was formed in an estuary environment because it has oyster fossils in and oysters only really lived in an estuary. The Purbeck bed has excellent layers and a fantastic fossil bed. It was formed 147 mya and has diagonal bedding after the collision of the Eurasian and African plates to form the Alps 65mya. This caused the bedding to go at a slant.

Next is the Wealden Bed. This has conglomerate, meaning rocks with "stuff" in. In this case, pebbles are present, meaning that the rock was formed in a high-energy environment. On top of this, it has coal in the rocks, which only forms on land. This tells us that the Wealden bed was formed by a river 140 mya.

Then, there is Greeensand. This is sandstone stained green by the mineral glauconite, and it can only form in deepish waters. It formed 125 mya but is easily eroded away.

Finally, there are chalk cliffs from 97 mya. Mainly calcite, chalk forms in the sea.

So why does the water level rise and drop? It is evidence of an ice age there at some point, when glaciers took in the water, then melted again.

Coves are formed when the hard rock (Portland Stone) is finally eroded away, leaving the soft rocks (greensand, chalk) exposed and the circular shape is formed.

Day 2
This was a day in the lab. We started off with rock ID, before moving on to oil reservoirs and the subsurface. However, this was not lab work as one might expect; it was interesting with fun activities. Oil might seem like an odd topic on a nature blog, but oil is in the natural world and the same principles apply to CO2 trapping. So what would an ideal oil reservoir look like? Well, the reservoir rock would be something like sandstone: porous (has holes) and permeable (the holes are well connected. Then, the reservoir rock would have a trap rock of shale, which is impermeable and non porous. This is, as the name suggests, to trap the oil from escaping from the reservoir rock. Then, a geological feature such as a fault line or anticline makes the most of this rock layering. Here, you can see what a fault does with this plasticine. If the green is the reservoir rock and the red is the cap/seal rock, then the green rock is covered from all sides, ensuring no oil escapes, or liquid CO2, for that matter.

Anticlines have their benefits shown in this experiment. The "sad face" structure means the commodity is trapped, as with the air in this experiment.

Then, we created an "ideal reservoir" with items such as rice krispies and plasticine!

Day 3
In the morning, we started off by looking at tectonic plates. With volcanoes, the larger the magma chamber is, the more devastating the eruption will be. However, although small chambers will still be explosive, they won't be as devastating. The deadliest volcano on Earth at the moment is in Yellowstone.
We also looked at evidence for Pangea, one of the previous supercontinents; there will be more supercontinents to come, with the  continents going through a cycle of getting further away and coming back together. A band of fossils run across the planet, and across the continents, showing that the animals once lived in the same place. Also, the continents fit together like a puzzle, and the rocks of the eastern coast of Brazil are the same as the rocks on the west coast of Africa. This shows that the rocks were once in the same place. Finally, evidence of past climates shows that some areas that are now quite far apart were identical.
In the afternoon, we went out on the RV (Research Vessel) Callista, into the estuary of Southampton and slightly into the Solent. After measuring salinity, which didn't really work thanks to gigantic waves being created by industrial oil tankers, we moved on to trawling to look at life in the water. This certainly came up trumps. Many Velvet swimming crabs were caught, along with the usual mussels, as well as a red spider crab, a pipefish, various sea squirts and a young dragon goby. Excellent! Also, worms were caught, and after looking at them under a microscope, we put them back in the sea, unchanged from their terrestrial experience. Then, finally, we did a plankton trawl. PLANKTON IS NOT ALL MICROSCOPIC. Plankton means "wanderer" so most jellyfish, regardless of if they are 1ft or 100ft are plankton. However, the image a little bit below is from 3ml or so of water; imagine how much you are swallowing in a mouthful of seawater!
Pipefish-closely related to seahorses



Finally, on day 4, we gave our presentations. Ours was on Lulworth Cove (thanks Zbigniew, Will, Maisy and Harry for a great presentation)!

Overall, 'twas an excellent couple of days, and below are some photos from Lulworth.


Durdle Dor, just down the coast
Diagonal bedding thanks to Alpine Orogeny 65mya

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