Filey's Jurassic Coast

The Filey Bay Research Group


"There is a rich untapped reservoir of history, Geology and Archaeology which is unique to our area" - said Tony Green of the Filey Bay Research Group commenting on the discovery of a Plesiosaur in the cliffs to the South of Filey. 

Filey Bay is the home to the Jurassic Coast , with the Geologically important Filey Brigg to the north of the bay and to the South, the famed Speeton clay cliffs, and following on from a fault line that roughly bisects the Bay in an easterly direction, the white chalk stone cliffs of the Cretaceous period leading to Flamborough Head. You can trace back in time when the dinosaurs trod the ooze of the river estuaries here over 140 million years ago.  The Jurassic is the second epoch of the Mesozoic era, lasting for 45 million years during which dinosaurs and ammonites flourished; from French jurassique from the Jura mountain range in eastern France.

In 2001
he substantially complete skeleton of a plesiosaur was found by an amateur collector, Nigel Armstrong in the Speeton clay. In an  excavation organised by Will Watts the Dinosaur coast Officer and Dr Phil Manning of the Yorkshire Museum.  The well preserved skeleton was removed from the  clay in one block weighing about one and a half tons. The skeleton was identified as being that of an elasmasaur a long necked plesiosaur of which there are several types.  At this time, there is a gap in our knowledge about these animals between 100 million years ago and 175 million years ago  and  this find can shed light on this unknown period.   This skeleton was removed from the lower beds of Speeton clay and is about 140 million years old.

 Dr  Manning was quoted as saying "To find such an important specimen with so many bones in place is fantastic, this creature should go a long way to filling many of the holes in the evolution of this group" and it is reported that this is the view shared by Mark Evans of Leicester Museums who is one of the plesiosaur experts to visit the site who said  " We know about these creatures from 200 million years ago from places like Whitby and from 90 million years ago from the USA, but there is a gap in their evolution.  This is a missing link in the plesiosaur story". 

The Speeton Clay beds are a popular place for fossil hunters, it is recommended that you look on the friends of Speeton Clay website link below for a fully comprehensive list of fossil types and detailed information about the clay itself.

WARNING to fossil hunters - the Speeton clay cliffs are dangerously unstable and it is unwise to venture close to them - you have been warned!

Speeton Clay cliffs Uncoiled Aegocriocer  in Speeton Clay Belemnites in Speeton Clay

For more information on Speeton clay and the fossils go to Friends of Speeton Clay    Adam Stuart Smith is acknowledged for the picture of the plesiosaur.


Filey Brigg looking to the west

Because of its geological importance, Filey Brigg to the north of the Bay is a site of Special Scientific Interest (SSSI) and is also designated as a local Nature Reserve.  In the Jurassic period of about 150 million years ago the hard rocks were laid down as silt and the Brigg and Carr Naze were built up by layers of material that were laid down over the subsequent millennia.

The Brigg consists of the hard rocks jutting out to sea in the form of a peninsula topped by the "Boulder Clay" cliffs known as Carr Naze.  The Brigg and Carr Naze are easily identifiable and they form a recognisable feature that readily identifies with the town of Filey.

The Filey Brigg  Geological Timeline

  Like all stratified rocks, the rocks on the Brigg are formed in layers that can be recognised, the top layer is the clay or Glacial Till that was brought down by the glaciers during the last Ice Age that finished about 10.000 years ago.  contained in this till are erratics or isolated rocks and stones that are mixed up in the clay and now form part of the beach at Filey as they have been washed out of the cliffs.
  The next layer down is a rubble layer which was formed by the freeze and thaw action on the upper level Hambleton Oolite below it (from New Latin oolites literally 'egg stone'.)
   Upper level Hambleton Oolite  upper is a limestone and within it are to be found fossils of bivalves and ammonites.
  The Birdsall Calcareous Grit is a very hard rock and is the lowest visible layer to the left hand side of the Brigg
  Next is the Lower level Hambleton Oolite consist of shell beds that were formed when warm waters seas the area.
  Below this layer are what are termed as the passage beds which were the product of the area being covered by a river delta.
  Next we have the Lower Calcareous Grit which was formed when a warm shallow sea covered the area.


The first picture shows the weathered Glacial till, the second picture below shows the rubble layer formed by freeze and thaw action above the stratified rock and below the Till on the south face of Carr Naze.  The third picture shows fossils amongst fossilised worm burrows in stratified rock.  The worm burrows have filled with a harder material and the softer material round them have weathered away at a greater rate leaving the burrows exposed above the surface of the rock.

Carr Naze Glacial Till eroded and etched in snow

Rubble layer below the till

Fossil bivalves in sedimentary rocks

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