Pinhay Bay is both geologically interesting and certainly a less popular location than nearby Lyme Regis. It can provide a good variety of fossils to be found, ranging from Triassic rocks, the Jurassic Lower Lias (fish, ammonites, shells and belemnites) and the Cretaceous Chalk (echinoids, gastropods and bivalves).
♦ Pinhay Bay can be reached by walking along the coast, westwards from Monmouth Beach, (just west of Lyme Regis town), along Chippel Bay (also featured on this website) to the next bay
♦ Once you pass the headland at Chippel Bay, the next bay is Pinhay Bay.
♦ This location is accessed by a long walk and, therefore, is only suitable for older children and certainly not suitable for those with walking difficulties
♦ Ref: 50.71294°N, 2.96478°W
FIND FREQUENCY: ♦♦♦ – The variety of geology at Pinhay Bay means you never quite know what you might find. Echinoids from the overlying Chalk are probably the most common find but ammonites from the Blue Lias can be found and lovely examples of some very large ones can be seen on the wave cut platform. (Do not hammer these – leave them to be enjoyed by others. Hammering into the rock is strictly forbidden in any case). Jurassic bivalves are quite common finds.
CHILDREN: ♦♦ – This location is accessed by a long walk and, therefore, is only suitable for older children.
ACCESS: ♦♦ – It is a long walk to this site along the beach from Lyme Regis or Monmouth Bay (just west of Lyme Regis town). Please check tide times.Visits should certainly only be made on a falling tide and consulting a tide timetable is absolutely essential, prior to your visit, to ensure a safe return. TYPE: – Most fossils are found in fallen blocks, which can be seen and examined on the foreshore or at the bottom of the cliffs in the scree. During scouring conditions, the Lias is exposed as ledges on the foreshore and these yield ammonites, many of which are quite large (do not try to extract these).
Fossils from the Triassic are generally unspectacular and mostly comprise of small bivalves, indicative of brackish and fully marine conditions at the time of deposition. At the western end of Pinhay Bay, a fault exposes the Jurassic Blue Lias, which is downthrown against the Triassic Langport Member. At its base is a bone-bed, occasionally yielding marine reptilian and ammonite fossils. At the head of Pinhay Bay, Triassic beds exposed on the foreshore can yield a range of bivalves.
The ammonite, Coroniceras bucklandi, from the lower Sinemurian Stage of the Blue Lias Formation is commonly found on the foreshore or among cliff falls at Pinhay Bay.
It is more difficult to find fossils in the Lias here than at Chippel Bay, as the beds are higher up. However, cliff falls can yield ammonites (some quite large) and nautili.These Hettangian-aged lower beds of the Blue Lias are known as the Pre-Planorbis Beds. The main fossil here is the oyster, Liostrea hisingeri, along with other bivalves, found in among the rock debris and on the foreshore.
Many fossils can also be collected from fallen blocks of Chalk at Pinhay, including echinoids, shells and crinoids. A range of fossils can also be found in the Upper Greensand chert beds from the top of the Lower Cretaceous (Albian), but these are often very poorly preserved.
West of Seven Rock Point, younger rocks contain the ammonite Psiloceras. In the UK, these are regarded as marking the base of the Jurassic.
At the head of Pinhay Bay, Triassic beds exposed on the foreshore can yield a range of bivalves.
Walking into Pinhay Bay from Lyme Regis, the junction of the Triassic (Penarth Group) with the overlying Jurassic strata of the Blue Lias Formation is found. The actual boundary sits within laminated limestones and shales, about 2.5 metres above the top of the clearly visible White Lias Formation, of the Langport Member, but the boundary is not conspicuous. This late Triassic limestone of the White Lias Formation lies below the Blue Lias and is eventually cut by a fault, so it is not visible to the west of the bay.
The Triassic rocks of the Penarth Group, are found on the foreshore and at the base of the cliffs. These Rhaetian aged rocks contain a range of compacted moulds of small aragonitic bivalves and gastropods, including Rhaotavicula contorta, Chlamys valonensis and Protocardia rhaetica, which can all be found.
The White Lias (Langport Member) is clearly seen in the cliff as pale green or grey limestones. White Lias is a rare, fine-grained form of limestone and getting the name ‘lias’ from the quarrymen’s dialect for ‘layers’, referring to its natural state when quarried. White Lias is part of the Penarth Group, a multi-layered bed of stone formed from shale and limestone. At its base is a bone-bed yielding ancient marine, reptilian and ammonites, although such occurrences at Pinhay Bay are seldom.
Walking west of Seven Rock Point, younger rocks can be seen above. These overlie the 19m of Blue Lias, and include Cretaceous Upper Greensand and the Chalk from the Lewes Nodular Chalk and the basal part of the overlying Seaford Chalk Formation from the Upper Turonian to the Coniacian. These beds are not accessible but fallen blocks on the beach can reveal a range of fossils.
Visits should certainly only be made on a falling tide and consulting a tide timetable is absolutely essential, prior to your visit.
Common sense when collecting at all locations should always be used and prior knowledge of tide times is essential. The two headlands at Pinhay Bay and the headland between Pinhay and Chippel Bays are often reached by the sea at high tide. Therefore, you should ensure that you can return in adequate time to pass these points, especially since this location involves long walks.
As with any visit to the coastal sections of West Dorset, the most obvious hazard is that of falling rocks from the cliffs. The risk is greater in wet, or after very wet, weather. Places on the beach where fresh falls are evident should be avoided.
In addition, falling rocks and mudslides from the high cliffs are a risk. If using a hammer, stay away from the cliff face, as sound vibrations can cause rocks to fall from the cliff.
Due to the range of both soft and hard layers at Pinhay, it is best to take both a hammer and a pick, together with a chisel and safety goggles. A lump hammer may come in useful, as there are a number of large chalk boulders, which can be split. For fossils from the older harder chalk, small bags are fine for getting them home. However, fossils from the softer, younger Chalk and Lias can be much more fragile, so these should be carefully wrapped and placed in containers or individual bags.
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 – Pinhay Bay