Bob Jamieson dot Net » Borders09

Borders Trip Part 5: Wrap Up and Next Time

Bob — Sat, 13 Jun 2009 17:36:09 +0000

In just a day and a half in the Borders we managed to visit fascinating geology ranging from the Ordovician through to the Quaternary. However, as you can see from these write ups it is painfully clear that we lacked the time to do it in any detail. We could have spent an entire day at Burnmouth wandering down the coast; another climbing the Eildons (like I said, I want a bit of Riebeckite-Felsite); one down the coast at Scremerston just south of Berwick collecting crinoid stems and another at Dob’s Linn and Grey Mare’s Tail looking at Quaternary landscapes and the North Trench. There are many more places we could have visited – we could have travelled up the coast to the volcanic hills and islands of North Berwick; down to Jedburgh to complete the Hutton’s Unconformity trifecta or to see some of the volcanic vents along the coast (eg at Coldingham).

We have loads of beautiful geology in our backyards here in Scotland, and there’s so much of it I still want to see. We’ll hopefully make another, longer, trip down at some point in the future. Stay tuned.

Homeward Bound

Borders Trip Part 4: Dob’s Linn

Bob — Sat, 13 Jun 2009 16:48:27 +0000

On Wednesday afternoon we drove across to Troon, travelling via Moffat so that we could visit the Ordovician-Silurian GSSP at Dob’s Linn (55.4400°N 3.2700°W according to the SSI). The region is a truly lovely glaciated landscape, with U-shaped valleys, hanging valleys, waterfalls etc. The area to the west of Dob’s Linn is a National Trust for Scotland Nature Reserve – Gray Mare’s Tail. A 60m waterfall falls down the side of the main valley, and walks lead up to the top of the waterfall to Loch Skeen (a corrie loch). It’s a lovely walk, and is a delightful example of textbook glaciated landforms (including a kettle hole hidden off to the right of the path just before the loch). The area is also of great ornithological interest thanks to its peregrine falcons, ring ouzel(s) (not sure how to pluralise that) and black grouse. It’s a delightful walk up there – unfortunately we didn’t have time to do the whole thing on this particular occasion, so we simply parked at Dob’s Linn. I previously went up there as part of a joint Advanced Higher Geography/Biology field trip in high school.

Anyway, back to our little excursion. We parked the car at the inconspicuous parking spot next to Dob’s Linn (the little valley is almost completely unsignposted or marked in any way – probably to help preserve it).

Dob's Linn from the road

We wandered up through the valley, finding the occasional graptolite rich fragment amongst the large scree slopes of black shale. Turning left we climbed up the Linn branch (a warning to people wanting to follow us, this involves clambering round some steep scree slopes – it’s not the safest excursion for the young or infirm and is extremely unwise to do alone). This branch of the gorge is really quite lovely, both geologically and aesthetically:

Some lovely, slightly folded shales to the South side of the branch

Ripple Marks (I've cheated here, this is a photo from a prior visit)

The Waterfall at the End of the Branch

That waterfall was particularly lovely last time I visited the area, in the deepest darkest Scottish Winter:

Frozen Waterfall

There are two excavated areas in Dob’s Linn: the Linn trench and the North trench. Both of these trenches show large sections of the strata, which have been examined and catalogued in detail by Lapworth and later Williams. Time didn’t allow us the opportunity to examine the North trench, however we were able to see the Linn branch trench, and examine the scree slope below it – within which many Graptolite specimens could be found.

The Linn Branch Trench

This photograph covers the border between the Ordovician (from where the photograph was taken) and the Silurian (where Hazel is sitting). Somewhere between us (I can’t put my finger on exactly where) is the FAD of Akidograptus Ascensus – the acknowledged boundary or ‘golden spike’.

After this we clambered back down and drove west to Moffat then back up the west coast. It’s worth noting that there are a great deal of excellent examples of slope failure along the road to Moffat (this area would make a fantastic day trip for a geography or geology class).

Following are a number of photographs of samples obtained from the loose scree material:

Some small fragmented graptolites - few specimens are preserved completely intact

More Examples

Not entirely sure what these are - any suggestions?

Layer of pyrite within the shale

These shales are really lovely, you can pull apart layers with your hands to reveal a new layer filled with graptolites or, as above, pyrite.

Borders Trip Part 3: The Eildon Hills

Bob — Fri, 12 Jun 2009 20:41:52 +0000

Early (well…) on Wednesday we drove a couple of miles up the road to the Eildon Hills – a journey which in no way involved travelling along a road that was closed for maintenance. We parked by the reservoir to the West of the Eildons – probably the best spot to start a walk.

Our Transport - The Green Blur, and our mascot - Trevor the Trilobite

Once again we were incredibly pushed for time; so much so that we didn’t have time to climb up the Eildons, instead contenting ourselves with a view from afar. However, that didn’t stop us from examining some of the geology of the area. Across the road from where we parked is Bowdenmoor Quarry; a quarried mass of Sanidine-Trachyte in Silurian country rocks which shares its origin with the Eildon Hills themselves. They were all part of the same intermediate-acidic layered lacolith (with one exception, which I’ll get to shortly).

The Quarry (picture by Hazel Scott)

I collected some nice samples of Sanidine-Trachyte here:

Sanidine-trachyte - note the phenocrysts

Since we had to get moving, we headed up the road, but not before snapping some more pics.

The Mid (lacolith) and Little (vent) Hills

The largest hill (left) is a part of the lacolith, consisting of layered sheets of trachyte and felsite (I wish we’d had time to get a bit of the Riebeckite-felsite). The smaller hill on the right (which isn’t usually counted as one of the three Eildon hills) is actually a volcanic vent intruded later. It consists of a central core of basalt and quartz-porphyry as well as some agglomerate.

Before getting in the car to drive across to the west coast (via Dob’s Linn) we couldn’t pass up the opportunity for another photo.

Emma and I in front of the Wester Hill

Behind us is the reservoir (which I think is man-made) and behind that is the Wester Hill – another part of the lacolith.

Borders Trip Part 2: Siccar Point

Bob — Fri, 12 Jun 2009 15:36:09 +0000

After stopping in Eyemouth for a fish supper, and being attacked by Scotland’s biggest seagull, we drove up the coast to Siccar Point. Parking just outside the quarry we walked round to come at Siccar Point from the East (having driven right past the “proper” path). Making our way up from the East however let us see the “alternative” unconformity, which is arguably a better example of a classic angular unconformity.

The Alternative Unconformity

Since it was about 8:30pm we decided not to clamber down to it, as we were losing the light. Instead we climbed over the top to view the classic Siccar Point example of the unconformity.

Hutton's Unconformity

Again, since we were pressed for time and the cliff was in shadow we decided not to climb down and look at it close up. Instead we spent time posing for photos holding the unconformity:

Hutton's UC

Finally we walked back down the way we were supposed to have come up, stopping to look at the helpful sign explaining the whole thing.

Info Board

We then drove back up to Galashiels, and spent the night playing Guitar Hero.

Borders Trip Part 1: Burnmouth

Bob — Thu, 11 Jun 2009 21:45:00 +0000

Earlier this week Hazel and Emma joined me down in the Scottish Borders for a look at some interesting geology. On the first day we drove down to the coast to engage in some fossil hunting. Parking in Burnmouth, we walked South along the beaches and cliffs. I’d liked to have gone down as far as Scremerston just South of Berwick, but we were a bit pushed for time.

Burnmouth Beach

Unfortunately we arrived shortly before high tide, with most of the fossiliferous beds marked in our helpful guidebook (McAdam et al. 1992) drowned by the sea. Despite that, the cliffs to the South looked interesting so we ambled down there, stopping occasionally to look at the lovely micaceous sandstone pebbles covering the beach. Some of the features seen on the cliffs are shown below:

Steeply Dipping Micaceous Sandstone

Small Deformation Bands

Odd weathering effect (heterogeneous cementation?)

One of the interesting things found here (which none of us had encountered in the field before) was what appears to be a geode:

Geode

Cross Bedding was also evident in some of the rock; although it also varied from finely laminated to massive in sections.

Cross-Bedding

At this point we ran out of beach, so were forced to climb up on top of the cliffs to continue southwards.

Steeply Dipping Beds submerged by tides

We continued south, seeing some wonderful looking things from afar. However, due to a combination of high tides and being on top of a cliff we weren’t able to inspect them up close.

More reddish Sandstones

A Sea Stack colonised by Seagulls

This sea stack is apparently called the Maiden’s Stone and, from a distance, appears to be a cross-bedded sandstone.

We stopped for a quick snack above a ruined old cottage; which the map claims is an old fishery.

The view down from our picnic spot

It was around 18:00 now (we’d had a late start) so we decided to head back to the car, so that we would have time to visit our next two stops: The excellent Chippy in Eyemouth and Siccar Point.

Hazel and Emma

Recommended Reading:

McAdam, A. D., Clarkson, E. N. K., and Stone, P.. (1992). Scottish Borders Geology: an excursion guide. Scottish Academic Press.