Belemnite fossil in situ in Belemnite Marl at Seatown, Dorset, England.

Belemnites at Seatown

The most common fossils at Seatown on the Dorset coast are belemnites. These are bullet-shaped internal hard parts of a type of extinct cephalopod (think cuttlefish, squid and octopus). For a great deal of the length of the beach, the rock strata are hidden by debris falling down from layers above. There are lots of minor mudslides and landslips. However, as you get nearer to the western extremity of the beach, approaching Golden Cap, a continuous kerb-like, harder, and more calcareous stone layer makes an appearance. This is the Belemnite Stone that has been raised to view by a small anticlinal flexure. Below it are many layers of Belemnite Marl that can be seen in cross-section in the vertical face at the base of the cliff; and also extending out horizontally beneath the gravelly beach and exposed at low tide. They alternate light and dark layers. Fossils are abundant with belemnites predominating but ammonites are also common. The huge numbers of belemnites are thought to have resulted from mass die-offs following mating frenzies.

Cross-sections of belemnite fossils in the cliff at Seatown, Dorset, England.

Belemnite fossils in horizontal Belemnite Marl beds exposed at low tide in Seatown, Dorset, England.

Belemnite fossils in the Belemnite Marls at Seatown in Dorset, England.

Layers of belemnites and other fossils in the cliff at Seatown, Dorset, England.

Cliff face on the western shore at Seatown, Dorset, England

Belemnites with trace fossils at Seatown in Dorset, England.

Low tide at Seatown, Dorset, England, showing boulders and horizontal beds of Belemnite Marls.

Cliff with mudslides at Seatown in Dorset, England.

8 Replies to “Belemnites at Seatown”

aidymcglynn says:

April 24, 2016 at 11:09 pm

Amazing Jessica – so clear.

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Jeremy Sell says:

April 25, 2016 at 2:04 am

Great photos, this looks like an excellent fossil site.

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Jo Woolf says:

April 25, 2016 at 4:09 pm

Oh my goodness, look at those!! How exciting! Thank you for sharing these. I love the colour of the sand as well – such a contrast.

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Rolling Harbour says:

April 25, 2016 at 9:02 pm

*Feeling guilty* Somewhere around the house is a box of belemnites from Seatown harvested by our children when small – about the age of their own children now. Should we surreptitiously put them back I wonder? (The fossils, not the children…)

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winderjssc says:

April 25, 2016 at 9:46 pm

Thank you, Aidy.

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winderjssc says:

April 25, 2016 at 9:50 pm

Thank you, Jeremy. It is one of many excellent fossil-rich locations along the Dorset and Devon coasts, also known as the Jurassic Coast World Heritage Site.

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winderjssc says:

April 25, 2016 at 9:52 pm

Thank you, Jo. It is a great place.

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winderjssc says:

April 25, 2016 at 10:02 pm

I am sure there is no problem with keeping them, RH, the fossils and the children. There must be millions of belemnites constantly eroding out of the rocks. I am fairly certain that fossil collecting is allowed at Seatown as long as people don’t climb the cliffs or dig out specimens from there. There are plenty of boulders and stones with fossils lying on the beach.

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