Pembrokeshire geology

Structural geology of Little Haven and The Settlands The cliffs from Little Haven to Broad Haven (and northward) display a spectacular range of geological structures, folding, faulting and thrusting, mainly in the Lower Coal Measures. The relatively weak mudstone and shale-dominated sequences show much incompetent deformation: tight, thrusted and overturned folds, in contrast to the thicker, stronger, sandstones which have formed relatively open and concentric folds. This is a view of the Fox Hole anticline taken from beach level. The style of folding is open and concentric, largely due to the competent (strong) nature of the sandstone of which it is comprised. A thin coal in the core of the anticline has largely been extracted by mining. The sandstone displays a number of sedimentary features, including cross-bedding and channel erosion, formed by deposition in a high-energy delta distributary channel setting. Restoring the anticline to its 'unfolded' condition, these sedimentary structures then indicate a general current flow direction from south-west to north-east. Folding, faulting and thrusting make determination of the exact stratigraphic correlation of the Fox Hole sandstone difficult, but it is reasonably clear that this is the lowest stratigraphic unit in the Little Haven area and is well down in the Lower Coal Measures sequence.

Structural geology of Little Haven and The Settlands The cliffs from Little Haven to Broad Haven (and northward) display a spectacular range of geological structures, folding, faulting and thrusting, mainly in the Lower Coal Measures. The relatively weak mudstone and shale-dominated sequences show much incompetent deformation: tight, thrusted and overturned folds, in contrast to the thicker, stronger, sandstones which have formed relatively open and concentric folds. This is an annotated geological interpretation of the original photo here: www.ipernity.com/doc/earthwatcher/48414290 In this northerly view, the largely concentric Fox Hole anticline, comprised of orange-brown sandstone is visible left of centre. The core of the anticline has been at least partly formed by coal mining activity. To the right of the anticline, a tight syncline is developed (below the yellow house), followed by a tight anticline which has a shattered core, due to the 'space problem' of folding these relatively strong rocks. Photo comprised of two landscape photos stiched together with Photoshop software. Interpretation linework carried out using Affinity Designer software.

Structural geology of Little Haven and The Settlands The cliffs from Little Haven to Broad Haven (and northward) display a spectacular range of geological structures, folding, faulting and thrusting, mainly in the Lower Coal Measures. The relatively weak mudstone and shale-dominated sequences show much incompetent deformation: tight, thrusted and overturned folds, in contrast to the thicker, stronger, sandstones which have formed relatively open and concentric folds. In this northerly view, the largely concentric Fox Hole anticline, comprised of orange-brown sandstone is visible left of centre. The core of the anticline has been at least partly formed by coal mining activity. To the right of the anticline, a tight syncline is developed (below the yellow house), followed by a tight anticline which has a shattered core, due to the 'space problem' of folding these relatively strong rocks. A full geological interpretation is shown in the adjacent photo here: www.ipernity.com/doc/earthwatcher/50001258 Photo comprised of two landscape photos stiched together with Photoshop software.

Structural geology of Little Haven and The Settlands The cliffs from Little Haven to Broad Haven (and northward) display a spectacular range of geological structures, folding, faulting and thrusting, mainly in the Lower Coal Measures. The relatively weak mudstone and shale-dominated sequences show much incompetent deformation: tight, thrusted and overturned folds, in contrast to the thicker, stronger, sandstones which have formed relatively open and concentric folds. In this northerly view looking over Rooks Bay in the foreground, the largely concentric Fox Hole anticline is comprised of orange-brown sandstone is visible on the centre right. The cave in core of the anticline has been at least partly formed by coal mining activity. The large bay in the centre is The Settlands. The northern headland of the bay is known as 'The Rain' and consists mostly of sandstones dipping steeply southwards (towards the camera), but actually overturned to the north. Broad Haven beach is visible in the distance beyond The Rain just left of centre.

Structural geology of Little Haven and The Settlands The cliffs from Little Haven to Broad Haven (and northward) display a spectacular range of geological structures, folding, faulting and thrusting, mainly in the Lower Coal Measures. The relatively weak mudstone and shale-dominated sequences show much incompetent deformation: tight, thrusted and overturned folds, in contrast to the thicker, stronger, sandstones which have formed relatively open and concentric folds. In this northerly view, the largely concentric Fox Hole anticline is comprised of orange-brown sandstone is visible on the centre right. The cave in core of the anticline has been at least partly formed by coal mining activity. The large bay in the centre is The Settlands. The northern headland of the bay is known as 'The Rain' and consists mostly of sandstones dipping steeply southwards (towards the camera), but actually overturned to the north. Broad Haven beach is visible beyond The Rain towards the upper left.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. Heading north along the coast path from Rickets Head, the site of Trefrane Cliff Colliery comes into view, with its spoil heaps and prominent furnace chimney. The colliery worked the Cliff Vein coal seam, pieces of which can be readily found in the spoil heaps. Looking over St Brides Bay, Ramsey Island is visible on the skyline just right of centre.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. Heading north along the coast path from Rickets Head, the site of Trefrane Cliff Colliery comes into view, with its spoil heaps and prominent furnace chimney. The colliery worked the Cliff Vein coal seam, pieces of which can be readily found in the spoil heaps.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. Heading north along the coast path from Rickets Head, the site of Trefrane Cliff Colliery comes into view, with its spoil heaps and prominent furnace chimney. The colliery worked the Cliff Vein coal seam, pieces of which can be readily found in the spoil heaps.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. Heading north along the coast path from Rickets Head, the open expanse of Newgale Sands and the wide sweep of St Brides Bay dominates view. In this zoomed-in view over Newgale Sands, the pale coloured cliffs in the distance are Pre-Cambrian volcanics, with darker grey Cambrian sediments to the right (above the line of surf).

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. Heading north along the coast path from Rickets Head, the open expanse of Newgale Sands and the wide sweep of St Brides Bay dominates view. Ramsey Island is visible on the skyline on the extreme left; the summit of Carn Llidi just left of centre. Seaward dipping beds of the Pennant Sandstone Formation form the wave-cut platform in the foreground.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. This northward view from the coast path from Rickets Head shows Newgale Sands in the background. On the right of the photo, behind the fence is a spoil heap in the vicinity of the shaft of Black Cliff (Rickets Head) Colliery which worked the Black Cliff Vein.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. This southward panoramic view from the coast path shows Rickets Head on the right and St Brides Bay in the background. The present-day profile of the headland is a result of former coal mining activity and the removal of overburden to access the Rickets Head Vein coal which cropped out at the base of the sandstone which comprises the up-standing pillar of rock. The coast path climbs up from Rickets Head over the disturbed ground and spoil heaps visible in the foreground. On the left of the photo in the flatter grassy area, are old shafts and degraded, grassed-over, spoil heaps of Rickets Head Colliery which worked the underlying Black Cliff Vein. Stratigraphically, the rocks of Rickets Head are the highest (youngest) in the Carboniferous sequence of the Pembrokeshire coalfields.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. An end-on, westerly view of Rickets Head with St Brides Bay in the background. The present-day profile of the headland is a result of former coal mining activity and the removal of overburden to access the Rickets Head Vein coal which cropped out at the base of the sandstone which comprises the up-standing pillar of rock. Stratigraphically, the rocks of Rickets Head are the highest (youngest) in the Carboniferous sequence of the Pembrokeshire coalfields. The coast path climbs up over the disturbed ground and spoil heaps visible in the foreground.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. This northward panoramic view from the coast path shows Rickets Head. The westerly, seaward, dip of the strata (approx 20°) is well seen.The present-day profile of the headland is a result of former coal mining activity; the rounded gap in the centre of the photo is at least partly due to the removal of overburden to access the Rickets Head Vein coal. On the right of the photo, behind the fence are old shafts and degraded, grassed-over, spoil heaps of Rickets Head Colliery which worked the underlying Black Cliff Vein. Stratigraphically, the rocks of Rickets Head are the highest (youngest) in the Carboniferous sequence of the Pembrokeshire coalfields.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. The cliffs of Nolton Haven expose predominantly deltaic channel sandstones, often with highly erosive bases with coarse, rip-up, channel-lag deposits. The general dip is around 20° to the south-west.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. The cliffs of Nolton Haven expose predominantly deltaic channel sandstones, often with highly erosive bases with coarse, rip-up, channel-lag deposits. The general dip is around 20° to the south-west. This photo shows a cross-section view of a locally derived beach boulder consisting of a channel lag deposit with ironstone pebbles and fragments set in a pale grey coarse sandstone matrix. The boulder is approx. 50 cm thick.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. The cliffs of Nolton Haven expose predominantly deltaic channel sandstones, often with highly erosive bases with coarse, rip-up, channel-lag deposits. The general dip is around 20° to the south-west. This photo shows the uoper surface of a locally derived beach boulder consisting of a channel lag deposit with ironstone pebbles and fragments set in a pale grey coarse sandstone matrix.

Nolton Haven to Newgale The small Nolton-Newgale coalfield is separated by faulting from the main Pembrokeshire coalfield. It lies mostly within Pennant Sandstone Formation of the Upper Coal Measures rocks. The cliffs of Nolton Haven expose predominantly deltaic channel sandstones, often with highly erosive bases with coarse, rip-up, channel-lag deposits. The general dip is around 20° to the south-west. This photo shows planar laminated sandstones with an erosive base resting on the underlying sandstone unit. Planar laminated sandstones in this setting often indicate high energy, fast current flow. The photo is approx. 60 cm from top to bottom.