This is a good location where you can find ammonites and bivalves. It can be a very productive location when the conditions are right, yielding a wide range of ammonite species. Most fossils are found on the foreshore.
DIRECTIONS
♦ Head towards Runswick Bay down a very steep road to where there is a large car park from which there is direct access onto the foreshore. From here, head towards the cliffs and search the foreshore on the way.
♦ Postcode to car park: TS13 5HT, Google Maps
♦ What3Words: ///stopwatch.smirking.aimed
PROFILE INFO
FIND FREQUENCY: ♦♦♦ – Most fossils are found by splitting rocks using a hammer. They can also be found within rocks along the foreshore.
CHILDREN: ♦♦♦♦♦ – This location is recommended for families, as it is easy to access the shore.
ACCESS: ♦♦♦ – There is a short walk to the shore from the car park near the beach.
TYPE: – Most fossils can be found on the foreshore within boulders and rocks, but they are also commonly found in the cliff and in the scree slopes.
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FOSSIL HUNTING
The Early to Late Liassic rocks exposed at Runswick Bay, combined with easy access, extensive foreshore exposure and a high frequency of finds, make this one of the best family-friendly fossil collecting locations on the North Yorkshire coast. The gently curving bay, broad beach and regular rockfalls continually expose fresh material, meaning there is almost always something to be found with patience and careful searching.
The coastline surrounding Whitby is rightly considered a mecca for Jurassic marine fossil collectors. From Staithes to Ravenscar, the general fossil fauna is similar, reflecting deposition in a warm, shallow Jurassic sea. However, Runswick Bay is particularly well known for its abundance of well-preserved ammonites. Among the most common species found here is Dactylioceras tenuicostatum, a finely ribbed ammonite that often occurs in beautifully detailed preservation within nodules. Its tightly coiled shell and distinct ribbing make it an attractive and recognisable species for collectors of all ages.
Access to the beach is straightforward, with convenient parking close to the shoreline. Once on the beach, head east and begin searching among the rocks and beach rubble that stretch all the way towards Kettleness. Always remain aware of the tide, as sections of the foreshore can become cut off on a rising tide.
The key to successful collecting at Runswick Bay lies in locating the hard, ovate or spherical nodules scattered across the beach. These concretions formed around decaying organisms on the Jurassic seabed and often contain exceptionally well-preserved fossils. As the sea erodes the surrounding softer shale, these tougher nodules are released and rolled smooth by wave action. In some cases, the keel of the ammonite inside can be seen faintly on the surface of the nodule before it is opened — a helpful clue that you may have found a promising specimen.
Nodules can also sometimes be found protruding directly from fallen shale blocks on the beach, having weathered out of the bedrock. These can often be collected carefully without the need for excavation. When splitting nodules, a geological hammer should be used responsibly and with eye protection. A well-aimed, controlled strike around the centre seam of the nodule will usually cause it to split cleanly, revealing both the positive fossil and its matching negative impression — effectively giving you two halves of the specimen.
While ammonites are the most commonly encountered fossils within the nodules, Runswick Bay offers a broader range of marine life. The large oyster Gryphaea is frequently found, recognisable by its strongly curved, claw-like shell, often referred to as a “devil’s toenail.” Various other bivalves and molluscs can also be discovered within shale fragments or concretions. Belemnites — the internal guards of squid-like cephalopods — are also present and are typically found as smooth, bullet-shaped fossils weathered free from the softer rock.
Occasionally, Runswick Bay yields something even older in geological terms. Remains of Pleistocene mammals — such as mammoth or bison — are sometimes washed ashore after rough North Sea storms. These bones and teeth originate from submerged prehistoric landscapes beneath the North Sea and are carried in by strong tides. Although far less common than Jurassic fossils, such finds add another exciting dimension to collecting at this site.
GEOLOGY
Runswick Bay exposes an important and extensive sequence of Lower Jurassic rocks, representing deposition during the Early Jurassic period approximately 195–180 million years ago. The succession here spans the Pliensbachian Stage (commonly referred to as the Middle Lias in older terminology) and the Toarcian Stage (Upper Lias), recording several million years of environmental change within the Cleveland Basin.
The geology visible around the bay reflects repeated fluctuations in sea level, sediment supply and marine oxygen conditions, resulting in alternating mudstones, ironstones and organic-rich shales.
Pliensbachian (Middle Lias) – Cleveland Ironstone Formation
The older rocks exposed at Runswick Bay belong to the Cleveland Ironstone Formation of Pliensbachian age (approximately 190–183 million years old). These deposits represent shallow to moderately deep marine conditions within a broad epicontinental sea.
The Cleveland Ironstone Formation here includes:
- The Penny Nab Member
- The Kettleness Member
These members consist of alternating mudstones, siltstones and distinct ironstone bands. The ironstone seams formed during periods of reduced sediment input and chemical conditions that allowed iron to concentrate on the seabed. These bands are laterally persistent and historically significant, having been worked during the 19th century ironstone mining industry of the Cleveland district.
Sedimentologically, this formation is varied. It records shifts between quieter offshore deposition (fine mudstones) and more oxygenated phases when benthic faunas flourished. The repeated alternation of lithologies reflects cyclical environmental changes, possibly linked to sea-level fluctuations.
Toarcian (Upper Lias) – Whitby Mudstone Formation
Overlying the Cleveland Ironstone Formation are the darker, more organic-rich deposits of the Whitby Mudstone Formation, representing the Toarcian Stage (approximately 183–180 million years ago).
At Runswick Bay, this formation includes:
- Grey Shale Member
- Mulgrave Shale Member
- Alum Shale Member
These units consist predominantly of finely laminated marine mudstones and shales deposited in relatively deeper water conditions. Periodically, oxygen levels at the seabed were reduced, leading to the preservation of high organic content in certain layers. This is particularly evident in the Alum Shale Member, which is rich in organic matter and historically associated with alum production along the Yorkshire coast.
The Whitby Mudstone Formation is especially significant because it represents a time of widespread marine anoxia during the Early Jurassic, often referred to as the Toarcian Oceanic Anoxic Event. These conditions contributed to exceptional fossil preservation in some beds.
Stratigraphic Relationships in the Bay
At Runswick Bay, the interplay between the Cleveland Ironstone Formation below and the Whitby Mudstone Formation above can be observed in cliff sections and on the foreshore, depending on recent erosion and exposure.
The lower parts of the cliffs and reef platforms may reveal ironstone bands and associated mudstones of the Penny Nab and Kettleness Members. Higher in the sequence, the darker shales of the Whitby Mudstone Formation dominate, particularly in areas exposed during low tide or after cliff falls.
The foreshore platforms provide valuable three-dimensional views of bedding planes, jointing and sedimentary structures, allowing visitors to trace lateral changes in lithology across the bay.
SAFETY
Common sense when collecting at all locations should be used and knowledge of tide times is essential. This part of the coastline is very dangerous as a result of tidal conditions, so make sure you return before the tide turns. Keep away from the base of the cliffs, as rock falls are very common. Hard hats are recommended.
EQUIPMENT
At Runswick Bay, careful observation is key, as the most productive finds usually come from hard, ovate or spherical nodules scattered across the foreshore, particularly after winter storms have scoured the beach. A geological hammer (16–24 oz) is essential for splitting these nodules cleanly, and a flat chisel can help guide controlled blows along natural seams, while eye protection should always be worn to guard against flying fragments. Sturdy, waterproof footwear with good grip is important due to uneven rock surfaces and slippery algae, and it is vital to keep a close watch on the tide to avoid being cut off, especially when heading towards Kettleness. Any fossils collected should be carefully wrapped in paper or protective material and placed in a rigid container to prevent damage during transport.
CLEANING AND TREATING
Begin by removing any loose sediment very carefully using a soft toothbrush. Take your time, as many fossils—particularly pyritic specimens—are fragile and easily damaged. Once cleaned, fossils should be desalinated by soaking them in fresh water for at least 24 hours to remove residual salt. After soaking, allow specimens to dry naturally at room temperature. Do not dry them on radiators or other heat sources, as rapid drying can cause cracking or long-term damage.
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 a site of special scientific interest (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, download the PDF from Natural England
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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