Originally called the Belemnite Beds and the Stonebarrow Beds.

  The Belemnite Marls (averaging 23m), are a series of bluish-gray marls that are a lot paler than the Black Ven Marls that they rest upon. This is due to the Belemnite Marls having a much higher carbonate content (they are said to be kerogen rich).

  At the base of this division is the Apoderoceras Bed (Bed 105 - sometimes called the Armatus Limestone Bed). This is a 0.35m thick limestone bed that forms a reef at Westhay Water, called Hawkfish Ledge, that is revealed at low tide. Although formed during a time when the sea level was fairly deep, the Apoderoceras Bed and the Belemnite Stone bed were formed during a time when the sea had shallowed quite significantly. The Apoderoceras Bed also underwent erosion leading to non-sequence of deposition.

  Just down from the top of the division is Bed 120, the Pyritic Marl and Crumbly Bed. This bed forms a prominent lighter band along the base of Wear Cliffs between Seatown and Golden Cap.

  At the top of this division is the Belemnite Stone (Bed 121), which is a 0.15m thick laterally persisting limestone, that forms a reef at St. Gabriels Water, that is revealed at low tide.

  Throughout the Belemnite Marls there is a distinct colour variation between beds of lighter marl (containing a higher carbonate content), and the darker marls (containing a higher organic carbon content). It is thought that this sort of colour alternation was formed as a result of the 19,000-23,000 year long precession cycle of the earth's orbit. Calcium carbonate measurements through the Belemnite Marls (lower Pliensbachian) are characterised by two scales of cyclicity that can be firmly linked to orbital precession (20 ka) and the 123 ka component of eccentricity.

  Further understanding of how this formation was deposited can be obtained by study of the Milankovitch Theory.

 Belemnite Marl as found between Lyme Regis and Charmouth:

 Belemnite Marl as found between Charmouth and St. Gabriel's Mouth:

 Belemnite Marl as found between St. Gabriel's Mouth and Seatown:

 This division is famous for Belemnite fossils, including examples of Passaloteuthis and Hastites.

A 112mm long Passaloteuthis apiculata found in the
talus at the base of the Golden Cap exposure of the Green
Ammonite Bed. 

 Ammonite fossils are also common in this division and include the pyritised, compressed and keeled Tropidoceras, as well as Apoderoceras, Platypleuroceras, Beaniceras, Liparoceras, Lytoceras, Tragophylloceras, Tragophylloceras ibex, Uptonia jamesoni and the large Parainoceramus ventricosus.

 Also found is the gastropod Amberleya.

Zones, sub-zones and fossils

Beds, geology and fossils

Photographs

A cross section of Belemnite Stone [Bed 121] showing Belemnite fossils.	At Westhay Water, the Middle Marls of Beds 111 to 116 are seen. This 'marker' can be seen throughout all Belemnite Marl exposures.
Although the Belemnite Marl is fairly hard, cracks due to erosion often appear in the cliff face.	Then without warning, it collapses!
A 'lenticule' of the Pyritic Marl and Crumbly Marl Bed.
A fault line extending down from the Green Ammonite Bed into the Belemnite Marl, provides a weak point that is attacked by the sea. The softer Belemnite Marl is soon eroded away.
Taken a year later, the Belemnite Marl at beach level is covered with sand and shingle. It is only under Golden Cap that the Belemnite Marl 'ledge' is visible at low tide.
In Oct 2004 a landslip under Stonebarrow Hill exposes the middle marl bands of the Belemnite Marl on the newly exposed cliff face.