F

Glossary of geological terms

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Farewell Rock / Y Garreg Ddiffaith

Thick sandstone near the base of the Westphalian Stage of the upper Carboniferous Period.  Prominent within the valleys of the Mellte, Hepste and Nedd Fechan rivers.

Farlovian or Farlow Series / Cyfres Farlow

Local stage name of the upper Devonian during which the Plateau Beds were deposited. See Devonian timechart.

Ffairfach Grit / Grut Ffair-fach

Coarse sandstone laid down during the Llanvirn Epoch of the Ordovician Period.

Ffinnant Sandstone Formation / Ffurfiant Tywodfaen Ffinnant

A succession of sandstones and mudstones deposited at the end of the Wenlock Epoch of the Silurian Period.

Fibua Formation / Ffurfiant Ffibiwa

Mudstones and siltstones laid down during the Ludlow Epoch of the Silurian Period.

Flandrian (stage) / Fflandriaidd

The last 10,000 years of geological time, since the end of the last Ice Age.  Also known as the ‘post-glacial’.  See Quaternary timechart.