Lulworth Formation

Lulworth Formation
Stratigraphic range: Tithonian - Berriasian 152–139 Ma
Lulworth Cove, an area where the Lulworth Formation is exposed
TypeFormation
Unit ofPurbeck Group
Sub-units
  • Worbarrow Tout Member
  • Ridgway Member
  • Mupe Member
UnderliesDurlston Formation
OverliesPortland Stone Formation
ThicknessIn Dorset 27-63 metres, In Weald 86 m Vale of Wardour up to 15m
Lithology
PrimaryCalcarenite, Micrite, Mudstone, Marl
OtherGypsum
Location
RegionEngland
CountryUnited Kingdom
Type section
Named forLulworth
LocationWest side of Worbarrow Tout

The Lulworth Formation is a geologic formation in England. It dates from the late Tithonian to the mid Berriasian. It is a subunit of the Purbeck Group.[1] In Dorset, it consists of three members, which are in ascending order, the Mupe Member, the Ridgway Member, and the Warbarrow Tout Member. The Mupe Member is typically 11 to 16 m thick and largely consists of marls and micrites with interbeds of calcareous mudstone.[2] The Ridgeway Member is about 3 to 7 m thick and consists of in its western portion carbonaceous muds, marls and micrites, in the east the muds are replaced by micritic limestone.[3] The Warbarrow Tout Member is 17 to 39 m thick and consists of limestone at the base and micrite and mudstone for the rest of the sequence,[4] this member is the primary source of the vertebrate fossils within the formation.[5][6] Elsewhere the unit is undifferentiated.

  1. ^ "Lulworth Formation". BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 28 August 2018.
  2. ^ "Mupe Member". BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 28 August 2018.
  3. ^ "Ridgeway Member". BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 28 August 2018.
  4. ^ "Warbarrow Tout Member". BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 28 August 2018.
  5. ^ "Sunnydown Farm Quarry (clay: upper horizon; equivalent to DB 102/103 )". Paleobiology Database. Retrieved 28 August 2018.
  6. ^ "Mammal Bed, Durlston Bay (DB83)". Paleobiology Database. Retrieved 28 August 2018.