Type Group Other sandstones, siltstones Country Wales Overlies Harlech Grits Group | Thickness about 2400m Region northwest Wales Primary Mudstone | |
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Sub-units Dol-cyn-Afon Formation, Dolgellau Formation, Ffestiniog Flags Formation, Maentwrog Formation, Clogau Formation | ||
The Mawddach Group is a middle to upper Cambrian lithostratigraphic group (a sequence of rock strata) in Gwynedd, Wales. The name is derived from the river known as the Afon Mawddach.
Contents
Outcrops
The rocks are exposed across the Harlech Dome and southern Snowdonia.
Lithology and stratigraphy
The Group comprises around 2400m thickness of mudstones, sandstones and siltstones laid down in the marine Welsh Basin during the middle to late Cambrian period. The Group comprises (in descending order i.e. oldest last) the Dol-cyn-Afon Formation, the Dolgellau Formation, the Ffestiniog Flags Formation, the Maentwrog Formation and the Clogau Formation.
References
Mawddach Group Wikipedia(Text) CC BY-SA