Trewin, N. H. and Hurst, A. (Eds.) 2009. Excursion Guide to the Geology of East Sutherland and Caithness. Dunedin Academic Press, Edinburgh
The text for this demonstration page was provided by the Aberdeen Geological Society. Find out more information about the Aberdeen Geological Society's field guides on their website.
The localities covered by the excursions in this guide are shown on the Excursion Planner map
Coastal excursions, particularly those on the Jurassic rocks, require half to low tide to see features exposed on the wave-cut platform. In rough weather with an onshore wind some sections may not be safely accessible. At all times great care should be taken; wet grass and rocks in cliff areas are frequently very slippery. Tide times are printed in the local newspaper (Press and Journal) or tide tables can be consulted.
In late autumn and winter lack of daylight becomes a problem, with sufficient light for detailed work only available between 9 am and 3.30 pm. However, at midsummer the days are very long!
The main towns are Golspie, Brora and Helmsdale in the south of the area covered, and Wick and Thurso in the north. Helmsdale and Thurso are considered the best centres at which to stay. Tourist information is available in season in the main towns, or from VisitScotland through visithighlands.com where accommodation can be booked online.
The following geological and topographic maps cover the localities described in this guide. Topographic maps are generally available from bookshops and tourist offices, and geological maps are stocked by the Orcadian Stone Company in Golspie, or can be obtained from the British Geological Survey, Murchison House, West Mains Road, Edinburgh. Maps and other geological output can be ordered online from the BGS Bookshop, and maps and other information is increasingly available from BGS in digital format.
BGS 1:625 000 North sheet (covers the whole of Scotland).
BGS Sheet 58N 04W 1:250 000 Caithness (New series incorporating offshore geology).
BGS 1:50 000 Series
Sheet 103 Golspie
Sheet 110 Latheron
Sheet 116E Wick
Sheet 116W Thurso
Sheet 115E Reay
Sheet 115W (Not available)
BGS 1:25 000 Geology Series
Dounreay (bedrock)
Ordnance Survey 1:50 000 Series
Sheet 10 Strathnaver
Sheet 11 Thurso and Dunbeath
Sheet 12 Thurso and Wick
Sheet 17 Helmsdale and Strath of Kildonan
(There is considerable overlap between sheets 11 and 12, sheet 12 being the best value for Excursion 5.)
In the following list the main features covered by each excursion are presented in note form to enable the reader to scan the list for items of particular interest. This list can be used in conjunction with the locality map and list of times required for excursions. Composite excursions can then be constructed to cater for the interests of the party within the time available.
1. Trias to Lias
2. Brora Coal Formation to Balintore Formation
Itinerary 1 Brora Coal to Brora Arenaceous Fm. Brora Foreshore.
Itinerary 2 Brora Arenaceous Fm. S. bank of Brora River.
Itinerary 3 Brora Argillaceous Fm. N. bank of Brora River.
Itinerary 4 Balintore Fm. N. foreshore at Brora.
3. Upper Jurassic sedimentation controlled by the Helmsdale Fault
Itinerary 1 Kintradwell Boulder Beds, soft sediment deformation.
Itinerary 2 Sandy submarine 'turbidite fan' deposits, Allt na Cuile Sst.
Itinerary 3 'The Fallen Stack'; boulder beds and clast stratigraphy. Itin 4 Helmsdale Boulder Beds; Helmsdale Fault Zone.
4. Lower ORS and relation to Helmsdale Granite
5. Old Red Sandstone of Caithness
Itinerary 1 Achanarras fish bed at Achanarras Quarry, lacustrine laminites, lacustrine margin at Dirlot.
Itinerary 2 John o' Groats Sandstone, Wick Flagstones at Wick, Sarclet Group at Sarclet Haven.
Itinerary 3 Middle ORS cyclicity. Brims Ness, Holburn Head fish bed,
Pennyland Shore at Thurso, Dunnet Sandstone.
Itinerary 4 Basin margin deposits at Red Point, Port Skerra and Baligill; ORS on Moine basement. Sandside Bay, marginal lacustrine and aeolian.
6. Gold panning. Moine basement
The times quoted do not include driving times to the starting point. Times allow for discussion and close examination of the rocks — a quick look-see' excursion will take less time.
1. Golspie, Triassic–Lower Jurassic
2–3 hours. Low tide required.
2. Brora, Middle–Upper Jurassic
Itinerary 1. 3 hours. Low tide required for Localities 1, 2
Itinerary 2. 3 hours
Itinerary 3. 3 hours
Itinerary 4. 1 hour. Low tide required
3. Kintradwell–Helmsdale Upper Jurassic
Itinerary 1. 2 hours. Low tide required
Itinerary 2. 4 hours for full excursion. Low tide required for localities 3, 5, 6.
Itinerary 3. 2 hours. Low tide required
Itinerary 4. 1–2 hours for localities 1–4; half day for localities 1–9. Low tide required for all localities.
4. Ousdale Lower ORS
2 hours. Can be done en route to Excursion 5, Itinerary 1 from Helmsdale.
5. Caithness Old Red Sandstone
Itinerary 1. Achanarras, Dirlot. Half day minimum, but much longer if searching for fossil fish.
Itinerary 2. John o' Groats, Wick Sarclet. 1 Day. Low tide required at John o' Groats for localities 6, 7, 8.
Itinerary 3. Brims Ness to Dunnet Head. 1 Day. Low tide required for Brims Ness (Locality 11); Pennyland Shore, Thurso (Locality 13) and Clett Harbour (Locality 15).
Itinerary 4. Strathy to Red Point and Sandside Bay 1 Day. Low to half tide advisable for Port Skerra (Locality 18) and Sandside Bay.
6. Kildonan Gold
Half day minimum. Depends on time spent gold panning.
For those visiting the area for the first time, and those with limited time at their disposal, the following might be considered the highlights of the area, and the associated problems.
Jurassic
Lias at Golspie (Excursion 1)
Poor exposure due to sand cover in intertidal area.
Brora Coal to Balintore Fms. (Excursion 2)
Itinerary 1 and Itinerary 4 cover most of the succession, exposure is mainly on the foreshore amongst boulders, hence there are problems with seaweed and sand cover. River exposures (Itineraries. 2, 3) are particularly useful if tides are too high.
Upper Jurassic fault controlled sedimentation (Excursion 3) Kintradwell Boulder Beds. Itinerary 1.
Sandy delta-derived Tan' deposits of Allt na Cuile Sst. Itinerary 2, Localities 4–6.
'Fallen stack' at Portgower. Itinerary 3, Locality 4.
Helmsdale Boulder Beds. Itinerary 4, Localities 1–4.
All shore exposures are subject to variable sand cover and seaweed in late summer.
Devonian (Excursions 4 and 5)
Lower ORS. Ousdale arkose and Ousdale Mudstones. Excursion 4. Sarclet Group. Excursion 5, Itinerary 2.
Achanarras fish bed, Achanarras Quarry. Excursion 5, Itinerary 1.
Lacustrine margin, stromatolite coated breccia, Dirlot Castle. Excursion 5, Itinerary 1.
Wick Flagstones sedimentology and cycles, South Head Wick. Excursion 5, Itinerary 2.
Middle ORS cycles. Brims Ness and Thurso Shore. Excursion 5, Itinerary 3. Low tide needed.
Upper ORS fluvial deposits, Dunnet Head. Excursion 5. Itinerary 3.
Lacustrine margin unconformity at Red Point and Port Skerra. Excursion 5. Itinerary 4.
Aeolian sandstones and flagstone cyclicity, Sandside Bay. Excursion 5 Itinerary 4.
Basement and mineralisation
Gold at Kildonan. Excursion 6. (Problem, not a lot of gold)
Basement Geology. Moines and intrusives. Excursion 6.
Basement also seen at Baligill, Port Skerra and Red Point. Excursion 5, Itinerary 4.