Aust cliff

Aust, the best Triassic site for fossils in the UK

The Famous Red and White cliffs that can be seen when crossing the river Severn contain a highly productive bone bearing bed at the very top from the Rhaetian Penarth series. This bed is full of teeth, reptile and fish remains and is the most productive Triassic site in the UK.


♦ Aust is located on the eastern side of the Severn estuary, close to the eastern end of the Severn Bridge.
♦ Accessibility to the cliffs from Junction 1 of the M48 is through a steel gate with stile to the concrete causeway. Parking is on the B4461  Aust Wharf Road at Old Passage.
♦ Park on Passage Road (Old Passage).
♦ Head along Passage Road towards the bridge, until you get to the beach.
♦ Ref: 51.60334°N, 2.62888°W


FIND FREQUENCY: ♦♦♦♦♦ – Fossils are regularly found at Aust, just a small amount of the famous bone bed can yield a high number of teeth, coprolites and bone fragments, and even if you cannot find any of these blocks, there is plenty of carboniferous molluscs to search for. The blocks of Aust bone bed are highly collected, so are usually quickly broken down by collectors. However, the broken down smaller pieces of bone bed can usually be broken down further!
Aust is suitable for children, provided they are supervised by an adult, keep to the Southern side of the bridge and DO NOT walk round to the northern side, keep away from the cliffs at Aust and mud flats.
ACCESS: ♦♦♦♦ – Aust is easy to access, providing that you stick to the Southern side. The Northern side is much more difficult to access and should only be done by experienced collectors, wearing appropriate footwear. There are no toilets near Aust.
TYPE: – Fossils at Aust are found along the foreshore. Fossils are found in the beds at the top of the cliff, the rest of the cliff section is totally unfossiliferous, therefore you will need to search the blocks along the foreshore and areas of shingle.


The cliffs of Aust are at both the North and South side of the bridge. When you enter the foreshore, you are on the Southern side which is currently being washed out more than the Northern side. To access the northern side, you will need to wait until the tide is low enough to walk around the concrete bridge support. Take extreme care if accessing this area as it can be slippery with mud flats. Return before the tide turns to avoid the risk of being cut off.

Pleisosaur Paddle Bone

Look out for shells, and loose bones, teeth, or bone fragments in the areas of shingle. Occasionally you should come across large lumps of the bone bed though they are usually quite small as collectors have already split them down. You only need a small amount of the famous bone bed, to yield some finds. Common fossils are shark and fish teeth and fish scales and coprolites. Fragments of bone are also very common and often are from Ichthyosaur and Pleisiosaur remains, but identifiable bones are less common such as large vertebrae’s and leg bones. You can also find fossilised clams, and oysters at Aust. Aust is a very popular location for collecting fossils and because of this high competition means that the bone bed blocks are becoming harder to find. However, in recent times the South side of the bridge is regularly washing out, with fresh cliff falls and a good amount of material to search through.

Aust pleisosaur vertebrae.

The Red Marls are unfossilferous, so there is no point in searching within this layer. The bone bed comes from the top of the cliff at the base of the Lower Lias, and is unreachable, this location is dependent on cliff falls.



This Middle and Late Triassic and Early Jurassic site lies south (downstream) of the Severn Bridge and can be seen as the familiar white and red cliffs. It is one of the UK’s few productive Triassic fossil collecting localities.

Here, the red beds of the Mercia Mudstone Group (formerly called Keuper Marls) form the Branscombe Mudstone Formation (206 -­‐ 221 Ma) from the cliff base, passing up to the green-­‐grey beds of the Blue Anchor Formation (206 – 221 Ma), (formerly called Tea Green Marls). Then rest the darker, then lighter, grey beds of the Penarth Group: the Westbury Formation and Cotham Member, (formerly called Rhaetic Beds) from the Late Triassic or Rhaetian (206 – 210 Ma). At the cliff top are the light brown beds of the Blue Lias Formation from the Early Jurassic.

The Branscombe Mudstone Formation at the cliff base is unfossiliferous. It is the beds of the Penarth Group: the Westbury Formation and Cotham Member, from which the Bone Bed emerges and is totally reliant on cliff falls.

The famous Red and White cliffs at Aust. The  Triassic bone beds are at the top.

Common sense when collecting at all locations should be taken and knowledge of tide times should always be noted. There are several dangers at Aust and these become more apparent if you plan to collect from the Northern side of the bridge. To get here, you will need to walk round the pillar of the Severn bridge when the tide is retreating. However, this is slippery, often having dangerous mud flats.  General safety at Aust is to keep away from the cliff as this can fall or crumble at any time, and to keep away from the mud on the foreshore which can be dangerous.

You can easily get cut off by the tide if you do not return before the tide starts to come in. Beware of the Severn bore (a large wave that happens a twice a year). Times for this are well advertised on the internet.


Many fossils can simply be collected from the foreshore, especially along the tide line. However, any large lumps of the bone bed will require strong tools to split them up. A good eye is often all you need, but tools are there to aid the fossil hunter, and you never know when you may need them.

Fossil Collecting at Aust

Although not an official right of way to the beach, the council and national grid allow permission to use the raised road, for walking, but not for any vehicles. An information board explaining this is at the end of this raised road.

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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