The sequence of the earlier lower old red sandstone (siluro‐devonian), north of milford haven, southwest dyfed (wales)

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Abstract
The Red Marls are renamed the Milford Haven Group (thickness approximately 2 · 4 km) and divided between the Red Cliff, Albion Sands, Lindsway Bay, Sandy Haven and Gelliswick Bay Formations, in ascending order. The lowest three, totalling approximately 230 m in thickness, are largely restricted to the Marloes area, where they succeed the marine Silurian rocks sharply and with a distinct facies change, indicative of a possibly substantial stratigraphical break. Northwards the Red Cliff and Albion Sands Formations are overlapped, the Lindsway Bay Formation in the Winsle area resting disconformably on marine Silurian rocks older than the youngest of the marine Silurian beds exposed at Marloes. The Sandy Haven and Gelliswick Bay Formations are more widely distributed and closely resemble the Red Marls of the Pembroke Peninsula and the main outcrop north of the Benton Fault. They are Gedinnian in age on the basis of ostracoderms, but the Gelliswick Bay Formation may range into the Siegenian. The thick Cosheston Group, which grades up from the Gelliswick Bay formation, probably represents the remainder of the Siegenian and may possibly be partly Emsian in age. The character of the Milford Haven Group lends no credence to the idea that allochthonous blocks are assembled in southwest Dyfed as the result of Variscan movements.