Milford Haven Group
   HOME

TheInfoList



OR:

The Milford Haven Group is a late Silurian to early Devonian
lithostratigraphic Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneou ...
group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...
(a sequence of rock strata) in west
Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...
. The name is derived from the estuary and town of Milford Haven in south Pembrokeshire. The Group comprises calcareous marls with occasional sandstones along with conglomerates and breccias. The Group
unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...
overlies rocks of the Gray Sandstone Group and comprises two different successions either side of the east–west aligned Ritec Fault To the north are (in ascending order) the Red Cliff, Albion Sands/Lindsway Bay, Sandy Haven and Gelliswick Bay formations. To the south are the Freshwater East, Moor Cliffs and Freshwater West formations. The Chapel Point Calcretes Member is recognised at the top of the Moor Cliffs Formation whilst the succeeding Freshwater West Formation is divided into a lower Conigar Pit Sandstone Member and an upper Rat Island Mudstone Member. The earlier of these formations are assigned to the Pridoli series of the Silurian. The top of the Silurian section is (according to some schemes) marked by the Townsend Tuff Member, above which lies the
Lochkovian The Lochkovian is one of three faunal stages in the Early Devonian Epoch. It lasted from 419.2 ± 3.2 million years ago to 410.8 ± 2.8 million years ago. It marked the beginning of the Devonian Period, and was followed by the Pragian Stage. It is ...
age strata. The Gelliswick Bay and Freshwater West formations are assigned to the local Dittonian series and straddle the internationally recognised Lochkovian and Pragian series. This suite of rocks is in turn conformably overlain by rocks of the
Cosheston Group The Cosheston Group is an early Devonian lithostratigraphy, lithostratigraphic group (stratigraphy), group (a sequence of rock strata) in west Wales. The name is derived from the village of Cosheston in south Pembrokeshire. The Group comprises (i ...
.Barclay, W.J. et al. 2005 ''The Old Red Sandstone of Great Britain'', Geological Conservation Review series, no 31 JNCC Peterborough. p212


References

{{Reflist Devonian System of Europe Silurian System of Europe Geology of Wales Geological groups of the United Kingdom