Helwell Bay at Doniford is one of the best locations in Somerset to collect the world-famous iridescent ammonites. The extensive foreshore also yields beautiful small white ammonites, reptile bones, and a variety of bivalves, making it a rewarding spot for fossil collectors.
DIRECTIONS
♦ The former car park at Doniford Bay that once provided easy access has been closed for several years.
♦ The only access to the steps in the centre of the bay is now from a small lay-by along the road with space for two cars. However, the road can be dangerous for families to walk along. If using this route, continue east along the road. You will pass the former parking area, now closed by a large gate. After rounding a bend, a footpath leads down to the steps to the beach. If you reach the farm shop, you have gone too far and missed the path.
♦ A safer and more convenient access point is from the Watchet end of the bay, where steps at the western end lead down to the foreshore. Parking is available at Watchet Harbour, and a cliff-top coastal path leads around the headland at Helwell Bay to the steps down to the shore.
♦ Postcode to the small Lay-by: TA23 0TQ; Google Maps
♦ Postcode to access from Watchet, Harbour Road Car Park, TA23 0AQ: Google Maps
♦ What3Words to best area: ///torched.major.nylon
PROFILE INFO
FIND FREQUENCY: ♦♦♦♦ – The foreshore at Helwell Bay (Doniford) can be very productive and the best time to collect is during scouring conditions. iridescent ammonites are commonly found.
CHILDREN: ♦♦♦♦ – Helwell Bay is ideal for family trips, however there can be a bit of a walk as the old car park is now closed. Access is either by Watchet, or a lay-by with a walk along a dangerous road.
ACCESS: ♦♦ – The old car park that once provided easy access has been closed for several years. A small lay-by with space for two cars remains along the road, but the road itself can be dangerous for families to walk along. This is now the only access point to the steps in the centre of the bay. For safer access, families are advised to approach from the Watchet end, where steps at the western end of the bay provide a better route down to the shore.
TYPE: – Helwell Bay is a foreshore location. Fossils are found in the rocks and shale on the foreshore and are best exposed during scouring tides.
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FOSSIL HUNTING
Helwell Bay is best known for its Early Jurassic ammonites, with most finds coming from the foreshore shales, fallen blocks, and nodule-rich layers exposed on scouring tides. Rather than searching the cliff (which can be unstable), focus on the intertidal zone: scan freshly broken shale slabs and the edges of hard, oval concretions where an ammonite’s outer whorl often “gives itself away” as a pale curve or ribbed band around the margin. If you split one fossiliferous block, it’s common to find several more ammonites within the same piece, as many horizons here contain dense “patches” of individuals. Some specimens are distorted or flattened by compaction, so splitting gently along bedding and natural cracks usually gives the best results.
Ammonite diversity can be excellent, and the site is famous for spectacular iridescent examples. Classic Helwell Bay finds include the early Jurassic ammonites Psiloceras planorbis and Caloceras johnstoni, which can preserve brilliant “mother-of-pearl” colours when the original shell layer survives. Other common ammonites on the Watchet–Doniford coast include Arnioceras, which can often be found in ledges and foreshore exposures. Keep an eye on the distribution of beds around the Watchet Fault: different horizons appear at different tidal levels and distances along the shore, and some of the best-preserved Psiloceras turn up on low-tide exposures in the right strata.
Helwell Bay isn’t only about ammonites. Bivalves are frequently found in the same foreshore beds and shale debris, with oysters and other shells sometimes occurring in clusters. Large, distinctive bivalves such as Plagiostoma gigas are recorded from this coast and can be an impressive find when weathered free. Belemnites may occur as well, though they can be less common in some of the beds compared with the ammonites and bivalves.
The wider Doniford–Helwell coastline has also produced important vertebrate material. Marine reptile bones do turn up, usually as isolated elements rather than tidy skeletons, and significant ichthyosaur finds from the Doniford coast have been documented from historic collecting and professional recovery. After heavy rain or storm tides, it’s always worth checking fresh cliff-fall debris (from a safe distance) and newly exposed foreshore blocks for bone-bearing nodules.
Finally, Helwell Bay’s “glacial beds” (more accurately, Ice Age fluvio-periglacial gravels and associated deposits) are part of what makes this locality special. These deposits have yielded mammal material in the past — including woolly mammoth remains — alongside evidence of ancient human activity. While they’re not the main fossil-hunting target for ammonite collectors, they add an extra layer of interest to the site’s history and explain why the bay can occasionally turn up unexpected Pleistocene finds.
Why some Helwell Bay ammonites are iridescent: the rainbow colours are not caused by oil in the shale. They’re a structural effect that occurs when the original nacreous (aragonite) shell layer is preserved as extremely thin, stacked micro-layers. Light reflecting within these layers produces interference colours, much like modern mother-of-pearl. Helwell Bay’s organic-rich shales and rapid burial conditions can sometimes protect that delicate shell structure from dissolving or recrystallising, which is why truly iridescent specimens are prized and comparatively uncommon.
GEOLOGY
Helwell Bay, near Doniford on the Somerset coast, exposes an interesting geological succession that spans from the Late Triassic into the Early Jurassic, together with younger Pleistocene deposits that cap the cliffs and valley sides. This combination of ancient marine sediments and much younger superficial deposits makes the bay geologically varied and particularly instructive. The foreshore reveals the older bedrock, while the cliffs display later sediments that were laid down during the Ice Age.
The oldest rocks visible at Helwell Bay belong to the Upper Triassic succession, including parts of the Mercia Mudstone Group and the overlying Penarth Group. These sediments were deposited in shallow coastal and lagoonal environments towards the end of the Triassic Period. The rocks often appear as red, green or grey mudstones and marls, reflecting fluctuating conditions between marine and marginal environments as the Jurassic sea began to spread across the region.
Above the Triassic beds lie Lower Jurassic rocks of the Lias Group. These include marls and mudstones that were deposited in a shallow marine environment during the early Jurassic seas that covered much of southern Britain. These beds can yield marine fossils, including bivalves, ammonites and other invertebrates preserved within nodules or weathered from the softer sediments.
Overlying the Jurassic and Triassic bedrock are much younger superficial deposits dating from the Pleistocene Ice Age. These deposits form much of the material seen in the cliffs and upper slopes around the bay. They consist mainly of gravels, sands and silts that were laid down by ancient river systems and subsequently modified by cold-climate processes during periods of periglacial activity. Freeze–thaw cycles and mass movement caused these sediments to slump and deform, producing the irregular and unstable cliff sections visible today.
These so-called “glacial” or periglacial deposits are particularly noticeable at the western end of Helwell Bay, where thick sequences of gravel and reworked sediment can be seen in the cliff exposures. Although the glaciers themselves did not reach this exact part of Somerset, the climate during the Ice Age was severe enough to produce extensive periglacial conditions, which shaped the landscape and reworked earlier sediments.
SAFETY
When collecting fossils at Helwell Bay, always remain aware of tide times and plan your visit accordingly, as parts of the foreshore can become cut off as the tide rises. The cliffs along this stretch of coast are unstable and prone to rockfall, so never work directly beneath them or close to freshly fallen debris. Many of the rocks and shale surfaces can also be very slippery, particularly when covered with algae or after rain, so sturdy footwear with good grip is essential.
At the extreme foreshore, especially during very low tides, areas of soft mud and silty sediment may be exposed. These can be deceptively unstable and it is possible to become stuck if you walk onto them. Always test the ground carefully before stepping onto muddy areas and avoid venturing too far onto soft surfaces. If in doubt, stay on firmer ground such as gravel, rock or compacted shale. Taking care on uneven rocks and being mindful of slippery and muddy areas will help ensure a safe and enjoyable fossil hunting trip.
EQUIPMENT
At Helwell Bay, most fossils are found loose on the foreshore or within naturally broken shale blocks, so heavy tools are often unnecessary. A small geological hammer and a flat splitting chisel can be useful for carefully opening shale slabs or nodules when needed, but gentle splitting along natural bedding planes is usually sufficient. The most important item to bring is something to protect your finds, as many of the ammonites — particularly the iridescent specimens — are extremely delicate. Wrapping materials such as tissue, newspaper or bubble wrap are essential, along with a rigid container or tray to prevent damage during transport. Sturdy footwear with good grip should also be worn due to uneven rocks and slippery surfaces, and collectors should always remain aware of the tide and avoid working directly beneath unstable cliff sections.
CLEANING AND TREATING
Let the specimen dry out so it’s easy to clean with a brush. Begin by removing any loose sediment very carefully using a soft toothbrush. Do not dry them on radiators or other heat sources, as rapid drying can cause cracking or long-term damage. We also advise against using water on the fragile flat ammonites.
Once fully dry, we recommend sealing fossils with Paraloid B-72, dissolved in acetone. This is a museum-grade consolidant that is widely available in pre-mixed bottles. Paraloid B-72 is stable, long-lasting, and does not yellow or react chemically over time. Importantly, it is also fully reversible, making it suitable for scientifically important or display-quality specimens.
Some collectors prefer to treat ammonites with artists’ varnish. This is acceptable for common species that are not of scientific importance, as it enhances colour and contrast and can make a specimen really “pop”. However, varnish is not reversible and is therefore not recommended for rarer or research-grade fossils.
ACCESS RIGHTS
This site is an SSSI. This means you can visit the site, but hammering the bedrock is not permitted. For full information about the reasons for the status of the site and restrictions please download the PDF from Natural England – SSSI Information
It is important to follow our ‘Code of Conduct’ when collecting fossils or visiting any site. Please also read our ‘Terms and Conditions‘
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