Waterloo Fossil Hunting

Waterloo’s low rocky shore, on the eastern side of Broadford Bay, offers a short introduction to Skye’s Early Jurassic marine fossils. Curved oyster shells, other bivalves and occasional ammonites occur in the shore rocks and loose material. The main interest is the Ardnish Formation, exposed in tidal pavements close to the village.

FIND FREQUENCY: ♦♦♦ – Shell-rich patches and weathered fossils occur among the Lower Jurassic shore rocks; ammonites are less straightforward to recognise and prepare.
CHILDREN: ♦♦♦♦ – A short approach makes Waterloo suitable for a supervised family visit in calm weather, but pools and slippery rocks need care.
ACCESS: ♦♦♦ – A path and gate lead from Waterloo road to the foreshore; parking is limited and the ground can be wet.
TYPE: Low rocky foreshore with sandstone, sandy limestone and shale; best examined on a falling tide around low water.

DIRECTIONS

♦ Approach Broadford on the A87 and take the minor road to Waterloo at Harrapool, on the eastern side of Broadford. Follow Waterloo road through the township towards its turning area. Continue on foot along the path beyond the road end and through the gate; where the surfaced route turns towards Breakish, leave it to the left across the short stretch of wet ground to reach the shore.

♦ Parking along Waterloo road is very limited. Walkhighlands’ approach to the Ardnish peninsula identifies the A87 lay-by opposite the Hebridean Inn as an alternative, followed by a walk east along the pavement to the Waterloo turning. Check signs and conditions on arrival, and do not use the inn’s private car park without permission. Keep passing places, the turning area, gateways and residents’ entrances clear.

♦ Locality reference: 57.23959°N, 5.87803°W.

FOSSIL HUNTING

The most recognisable fossils are the thick, curved shells of Gryphaea, commonly called devil’s toenails. The Scottish Geology Trust specifically records good examples at Waterloo. Look for the strongly curved larger valve and the much flatter smaller valve, and examine naturally weathered loose material before considering anything still attached to the rock.

Ammonites occur in the local succession, although exposed specimens may be incomplete casts or fragments. The Geological Survey recorded Arnioceras from the shore south of Rubha Achadh a’ Chùirn. This is a historical locality record, rather than a guarantee that identifiable examples will be found on a visit. Fossils in hard rock are often better photographed in place than damaged by attempted extraction.

Work slowly over naturally weathered sandy limestone and sandstone, where erosion can bring shell outlines, curved cross-sections and ribbed fragments into relief. Compare these with finer, layered shaly pieces; an ammonite may be represented by a curved or ribbed mould rather than a complete coiled shell. Mica can make broken surfaces glitter, but these shiny flakes are minerals. Photograph promising surfaces with a scale, and note the rock type, exact position and whether the find was loose or still in place.

Other bivalves and gastropods appear in the original locality photographs. Their precise collecting horizons were not recorded, so the photographs should not be used to assign all the illustrated specimens to one bed or geological stage. Shell-rich layers can be examined on weathered surfaces, but avoid prising up the foreshore slabs or hammering the bedrock.

The coral beds described at Ob Lusa and Lower Breakish belong to the older Breakish Formation. They should not be treated as a named collecting horizon on the Waterloo shore. Record where each loose specimen was found; loose material alone may not establish the bed from which it originally came.

A chronological record of fossil documentation and geological research connected with the Waterloo shore.

1910 – Waterloo shore fossils documented
The Geological Survey memoir catalogued Arnioceras specimens from the coast south of Rudh’ Achadh a’ Chuirn, identified as locality 10 in its fossil appendix. This is a documented historical fossil record from the Waterloo shore; the publication date does not establish when the specimens were first found.

1986 – Shore structures incorporated into a geological excursion
Brian Bell and John Harris’s field guide used the Waterloo approach to explain the Lower Jurassic coastal succession and its younger intrusions. The guide described a roughly 10 m-wide multiple dolerite dyke near the road-end and the small faults that disrupt the foreshore rocks.

1995 – An ammonite-bearing horizon traced to Waterloo
Nicol Morton and John Hudson published a detailed map of the coastal succession and described the prominent scarp of their Bed 30 traced south-westwards to the Waterloo road-end. This provides a direct correlation between the local shore and a measured sandstone-and-shale interval on the Ardnish Peninsula.

1998–1999 – The formation framework revised
A revision of the Lower Jurassic succession placed the former Upper Broadford Beds within an enlarged Pabay Shale Formation. Subsequent discussion proposed retaining the distinct micaceous rocks as the Ardnish Formation, the name later adopted in Geological Survey usage for the succession extending to Waterloo.

2004 – Waterloo’s place in the coastal succession clarified
A geological conservation synthesis mapped the Ardnish rocks south-westwards to Waterloo and reconciled different bed-numbering schemes. The horizon traced to the road-end became Bed 13, while the account emphasised the complications caused by faults, concealed intervals and uncertain correlations.

GEOLOGY

Waterloo’s fossil-bearing shore is part of the Ardnish Formation of the Lias Group. Modern field descriptions explicitly identify sandstone, sandy limestone and shale at Rubha Achadh a’ Chùirn, south-west of the Waterloo road-end. These marine rocks belong to the Sinemurian part of the Early Jurassic. The neighbouring Ardnish reference succession is dated mainly to the Semicostatum ammonite Zone.

The rocks were deposited on a marine shelf, with sand, silt and mud supplied from nearby land. Mica is a characteristic component, and some layers are rich in iron-bearing minerals or fossil shells. Different beds weather at different rates, producing the low, uneven pavements and reefs of the present foreshore. The oysters and ammonites record a varied marine community.

The strata dip gently towards the north-west and are interrupted by small faults. Much younger Paleocene dolerite dykes cut across them; a multiple dyke about 10 m wide is described at Bogha Mòr Achadh a’ Chuirn near the Waterloo road-end. Heating beside intrusions affected the sediments locally, but the whole shore should not be described as uniformly baked.

Older publications grouped these beds with the Upper Broadford Beds, and a 1998 scheme included them within an expanded Pabay Shale Formation. The separate Ardnish Formation is the name used here, following later Geological Survey usage. The Pliensbachian age and Ob Lusa Coral Bed attribution in the former locality account do not describe this Waterloo succession.

Explore Waterloo’s Ardnish Formation, its mapped bed correlations and younger intrusive rocks.

This account covers the Waterloo shore and its continuation to the road-end. Published mapping connects the local rocks with the Ardnish succession, but the detailed measured section lies farther north-east on the peninsula. The numbered intervals below explain those mapped correlations; their reference thicknesses are not measurements of a continuous section at Waterloo.

LIAS GROUP

The Lias Group contains the marine Early Jurassic succession. At Waterloo the relevant unit is the Ardnish Formation; neither the complete Lias Group nor its younger formations is exposed as a single local shore section.

ARDNISH FORMATION

Sandstone, siltstone and fissile micaceous mudstone are characteristic, with sandy limestone and fossil-rich layers on this shore. The BGS gives a regional formation thickness of 55–78 m, which is not a Waterloo exposure thickness. In the regional succession, the formation overlies the more carbonate-rich Breakish Formation and is overlain by Pabay Shale mudstones. No separate formal member is securely identified for this short shore.

Waterloo pavements and reefs. The Geological Survey described micaceous sandy limestone and calcareous sandstone in the reefs off Rudh’ Achadh a’ Chuirn. Modern descriptions confirm sandstone, sandy limestone and shale, interrupted by minor faults and dykes. The historical Arnioceras record comes from the coast south of the promontory. Separate records of Coroniceras lyra and Pleuromya east-north-east of it should not be transferred to the Waterloo pavements. None of these records establishes a numbered bed for each specimen.

Mapped package H: reference Beds 9–12. The published maps carry this package into the Waterloo coastal strip. The individual beds and covered interval are distinguished in the Ardnish reference log, not mapped separately across every Waterloo pavement. Their order, from lower to higher, is described below.

Bed 9: nodular sandstone and siltstone, 3.10 m in the reference section. Micaceous beds contain scattered small phosphatic nodules, abundant Arnioceras and Gryphaea, with Coroniceras lyra also recorded. The package forms a prominent reef in the measured Ardnish section. It corresponds to Bed 26 of Morton and Hudson’s 1995 scheme.

Bed 10: covered interval, approximately 10 m in the reference section. A muddy inlet interrupts the measured succession. Shale is inferred beneath the gap; this is not a continuously exposed shale bed. It corresponds to historical Bed 27.

Bed 11: micaceous sandstone and siltstone, 1.35 m in the reference section. The beds contain iron-rich berthierine ooids, termed chamosite in older descriptions, and a record of Coroniceras. This is historical Bed 28.

Bed 12: shelly silty shale, 1.50 m in the reference section. Micaceous shale contains bivalves, especially Gryphaea. A large Agassiceras superbum, exceeding 40 cm in diameter, was recorded from this bed on northern Ardnish and indicates the Scipionianum Subzone. That specimen is a reference-section record, not a documented Waterloo find. This is historical Bed 29.

Mapped package I: Bed 13, traced to the Waterloo road-end. This package comprises micaceous sandstone and silty shale with common ammonites. It is 9.85 m thick in the Ardnish reference log and corresponds to Morton and Hudson’s Bed 30. Its scarp was traced south-westwards across repeated minor-fault offsets to the road-end at NG 6660 2390. The reference log records Arnioceras nodulosum and Agassiceras scipionianum, with Euagassiceras terquemi higher in the package, spanning the Scipionianum and Sauzeanum subzones. This correlation does not mean the entire measured thickness is exposed beside the road.

Depositional setting and correlation limits. The Ardnish rocks record an offshore shelf near or below normal wave-base, with alternating finer and coarser sediment supply. The reference succession is predominantly lower Sinemurian, in the Semicostatum Zone. Numerous small faults and covered intervals complicate correlation. The full lower Ardnish log, its named ironstone and the older Ob Lusa and Ob Breakish coral beds should not be added to Waterloo as though all are exposed here.

Paleocene dykes and later shore cover. Much younger dolerite intrudes the Jurassic sedimentary rocks. At the northern approach, Bogha Mòr Achadh a’ Chuirn is formed by a roughly 10 m-wide multiple dyke trending north-north-west to south-south-east. Local heating beside intrusions and slight wider thermal alteration are distinct from the original marine deposition. Modern beach sediment and seaweed obscure parts of the bedrock and are not Jurassic stratigraphic units.

References
Peach, B. N. and colleagues (1910). The geology of Glenelg, Lochalsh and south-east part of Skye. Geological Survey memoir, Sheet 71, especially pp. 101 and 182–184.
Bell, B. R. and Harris, J. W. (1986). The Broadford area, in An excursion guide to the geology of the Isle of Skye.
Morton, N. and Hudson, J. D. (1995). Field guide to the Jurassic of the Isles of Raasay and Skye, Inner Hebrides, NW Scotland. In Field Geology of the British Jurassic, pp. 209–280; especially pp. 216–220 and figures 6 and 8.
Morton, N. (2004). Ob Lusa to Ardnish Coast, pp. 325–331, in British Lower Jurassic Stratigraphy, Chapter 8: The Hebrides Basin. Geological Conservation Review Series 30.
British Geological Survey. Ardnish Formation, BGS Lexicon.
Bell, B. Strath 1: Broadford Bay, Skye & Raasay Geology, especially p. 4.

SAFETY

The main hazards at Waterloo are the tide and slippery, uneven footing across the low rocky shore. Plan a visit for a falling tide, with time around low water, and check the day’s tide times and weather before setting out. Keep your route back to the shore access in view and return before the water reaches it. The open outlook is useful, but it does not remove the risk of rising water around low rock platforms. Avoid the seaweed-covered lower shore, deep pools and unstable slabs; do not try to lift or lever large blocks.

Wear footwear with a firm grip, carry waterproofs and supervise children closely beside pools and wet rock. The approach can be muddy and the foreshore is not a surfaced walking route. Leave in rough weather or poor visibility. Carry a charged phone in a waterproof pouch, tell someone your plans and do not rely on an old report of good mobile reception. In a coastal emergency, call 999 or 112 and ask for the Coastguard.

EQUIPMENT

Wear boots with a firm grip and bring waterproofs, a hand lens, a camera and a small scale for recording fossils in place. Carry tide information, a map, a charged phone and a small first-aid kit. The path is short, but wet ground and uneven rock make secure footwear more important than the distance suggests.

If collecting permission has been obtained, take labels, padding and small rigid boxes for permitted loose finds. Do not bring a heavy mallet or lever to open the bedrock: the most useful first step here is to inspect already exposed fossil surfaces without disturbing the shore.

CLEANING AND TREATING

For lawfully collected loose specimens, begin with gentle dry brushing. Keep fragile shell edges, matching fragments and matrix together, and label each find with its exact position and whether it came from loose material or a known layer. Avoid mixing Waterloo finds with material from the separate Ardnish or Ob Lusa sections.

Shaly matrix can split or crumble during soaking or rapid drying, while hard calcareous sandstone can grip a fossil firmly. Let wet material dry slowly and do not force it apart to chase an ammonite or large shell. Household acids, bleach and varnish can damage or obscure fossils. If a specimen needs substantial preparation, seek specialist advice before using tools; preserve significant or unusual finds and their contextual information.

IDENTIFY YOUR FINDS

FURTHER READING

Scottish Geology Trust: Jurassic oysters, including Waterloo
BGS: Ardnish Formation
Brian Bell: Broadford Bay geological excursion
Geological Conservation Review: the Hebrides Basin, including the Ob Lusa–Ardnish succession
1910 Geological Survey memoir: Glenelg, Lochalsh and south-east Skye

ACCESS RIGHTS

This guide concerns the shore reached from Waterloo road. NatureScot’s current mapped boundaries place the frontage around the published locality reference outside a Site of Special Scientific Interest and outside the Skye Nature Conservation Order. The Ob Lusa to Ardnish SSSI lies farther east, covering part of the Ardnish peninsula and the coast towards Ob Lusa. Check the official boundary map before extending a visit into those areas; collecting advice for Waterloo must not be assumed to apply throughout Broadford Bay.

Responsible access under the Scottish Outdoor Access Code does not give a right to extract or take away fossils. Obtain the landowner’s permission before collecting and follow the Scottish Fossil Code. Leave exposed bedrock intact, avoid digging into the shore and never remove material from walls. Observing and photographing fossils in place is a worthwhile visit in its own right; where collecting is permitted, keep to a few naturally loose specimens and record where each was found.

In an SSSI, collecting from protected bedrock requires NatureScot consent through the landowner, and restrictions can also apply to loose material. If permission or the applicable rules are unclear, do not collect. Leave unusual, large or potentially significant fossils in place, photograph them and seek expert advice. NatureScot’s Skye fossil guidance explains the separate restrictions protecting vertebrate fossils in areas covered by the Nature Conservation Order.

It is important to follow our Code of Conduct when collecting fossils or visiting any site. Please also read our Terms and Conditions.

LINKS

♦ Fossil Discussions
♦ Fossil Articles
♦ Buy Fossils, Tools and Equipment
♦ Buy Crystals, Meteorites, and Artefacts
♦ Join Fossil Hunts
♦ UK Fossils Network