This July Our year 10 GCSE Geologists had the opportunity to travel to Pembrokeshire to visit sites of geological interest. Here are our daily updates from the trip by our pupils, Miss Allman and Mr Peace.
Day 1:
We arrived in the principality and went straight to Stackpole Quay where we looked at sediments from the Carboniferous period. Deposited on a sea floor 350 million years ago, when the UK was located just south of the equators, they showed fossils of solitary and colonial corals, Gastropods and brachiopods. These sediments were then folded into this magnificent asymmetrical syncline!
Day 2:
Day 2 meant a trip to Freshwater East. We had identified that the rocks had been turned vertical due to the Variscan Orogeny before arriving. Once there we confirmed that by measuring dip and strike, and looked at a variety of sedimentary structures in the Old Red Sandstone telling us which rocks were oldest and which youngest.
We saw a 400 million year old river bed and the flute casts in the base, and were able to see how the beds had been moved some 20m by a fault.
A particular highlight was seeing the tracks left in late Silurian mudstone by a Eurypterid or sea scorpion.
We finished the day with a trip to St Anne’s Head to see a double fold. Special thanks went to Harvey for donating a tea bag or two to Mr Peace to save him from the insipid Welsh brew that had been provided!
Day 3:
Pupils spent the day on the beach at Marloes sands looking at marine sedimentary rocks from the Silurian (430 million years old) with some evidence of volcanic activity.
Everyone found some fossil corals and brachiopods which lived on the sea floor at this time and Mr Peace found the pygidium (tail) of a cheeky trilobite, his first ever. It may not look much in the photo, but if you know, you know!
Most importantly, Mr Peace paid his 10 tea bag debt to Harvey with an additional bag as interest.
Day 4:
Yesterday was a day of untold geological riches. Firstly, we visited the beautiful harbour of Porth Clais and investigated the rocks created by an intrusion of granite cut across by basalt dykes.
We then went up above the harbour and looked down on a sill intruded into the vertical sandstone beds at Ogof Golcha.
We finished by looking at the unconsolidated deposits in the cliff showed that sea level was up to 7m higher at times during the last interglacial period.
The day concluded with a beautiful cake and singing happy birthday to Jack.
Day 5:
Sadly time has defeated us, and I’m writing this approaching Swansea (Abertawe) on our way home.
This morning we looked at sandstones and shales formed on a tropical delta in the late Carboniferous. As vegetation died, it was rapidly buried and over time turned into coal, which was mined in the valleys of southern Wales.
The sediments were heavily faulted and folded and we saw one of Europe’s classic anticlines where we had a team photo with the legendary Sid Howells.
A very productive field visit with the troops identifying the following highlights:
3rd – Eurypterid tracks
2nd – the classic sill
1st – the naughty double fold at Cobblers Hole
We won’t miss:
3rd – veggie day
2nd – Charlie’s animal impressions
1st – insipid Welsh tea
