A geological and geomorphological tour

No Vestige of a beginning, no prospect of an end. A geological and geomorphological tour of Holyrood Park, Edinburgh

On Wednesday 26th August 2015 ten members (and one dog) went on a Geological and Geomorphological tour of Holyrood Park led by member Alistair McGowan, Hills of Hame We began by looking at some of the sedimentary rocks, which form the bedrock before the volcanic eruptions that created Arthur’s Seat, Edinburgh’s own extinct volcano. We saw the patterns of drying mud and ripples in the sand preserved in the rocks from around 350-360 Million years ago.

After a brief stop at Hunter’s Bog we headed uphill to look at some volcanic sills, different lava flows and fossils (see Figure 1). The fossils we looked at were Calamites, which are plants very similar to living horsetails - a sample of which Alistair had provided from his own garden. The fossils had been formed when hot lava flowed onto the boggy ground in which the prehistoric plants were living. The plants were essentially carbonised (see Figure 2) which their imprint being left in the fossil record.

At one stop we had the chance to look more closely at the rocks using a mixture of hand lenses, compass magnifiers and phone scopes. he phone scopes were a really big hit. They attach over the camera on a smart phone or tablet, you place the magnifier on the rock and the image of the magnified rock appears on the device screen. This means everyone in the group can see the same image at once, which is ideal for teaching and group interaction. I’ll definitely be investing in one of these little toys in future.

Given the number of Mountain Leaders in the party we simply had to visit the summit of Arthur’s Seat. Sadly, the views to the Hghlands were obscured by clouds but we could see a number of other geological features including the extinct volcanoes of North Berwick Law and Traprain Law along with great views to the Pentlands and Southern Uplands.

We didn’t linger long on the summit as although a clear and sunny evening it was incredibly windy so a quick descent was made stopping at the “Gutted Haddie” on the way down. This was the youngest feature we looked at. It was formed by water and rocks pouring down the hill during a massive storm around 200 years ago. The scar on the rocks is said to look like an opened up haddock, hence the name. Our tour finished off with a stop at Hutton’s Section probably the most famous geological site in Edinburgh. This volcanic sill provided the evidence that Arthur’s Seat was formed from magma intruded into much older layers of sedimentary rock.

On the walk back to the starting point we stopped off at Cat’s Nick, a fault where evidence of fluid movement along the fault lines can still be seen today. Don’t worry though the faults are no longer active.

It was a fun and informative evening. Thank you very much to Alistair and to the Mountain Training Association for taking time to provide the workshop.

Alistair will be running a full Continued Personal Development workshop Rocks, rivers and reivers: Landscape and human history in the Pentland Hills on Sunday 25th October meeting at the Flotterstone visitor centre.

Fiona Reid
Mountain Leader