Earthwatcher's photos with the keyword: cleavage

Druidston Haven geology: Cliff Section 1 interpretation Interpretation No.1 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. Photo No.1 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The background is a panoramic view of two photos stitched together using Photoshop software. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 1 Photo No.1 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. This is a panoramic view of two photos stitched together using Photoshop software. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 2 interpretation Interpretation No.2 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 2 Photo No.2 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 3 interpretation Interpretation No.3 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The sandstone beds seen in this photo show irregular slumped bases and load casts, thus confirming that these beds young to the south (right). The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 3 Photo No.3 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The sandstone beds seen in this photo show irregular slumped bases and load casts, thus confirming that these beds young to the south (right). The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 4 interpretation Interpretation No.4 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The sandstone beds seen in this photo show irregular slumped bases and load casts, thus confirming that these beds young to the south (right). The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 4 Photo No.4 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The sandstone beds seen in this photo show irregular slumped bases and load casts, thus confirming that these beds young to the south (right). The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 5 interpretation Interpretation No.5 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 5 Photo No.5 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. These photos show the section midway along the horst from the stream to the Southern Boundary Fault at the far end.

Druidston Haven geology: Cliff Section 6 interpretation Interpretation No.6 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. This photo shows the southern end of the horst, terminated by the Southern Boundary Fault; a significant structure with a throw (displacement) of at least 1500 metres to the south, bringing Namurian 'Millstone Grit Series' (upper Carboniferous) rocks into contact with the Ordovician shales.

Druidston Haven geology: Cliff Section 6 Photo No.6 of a series of six photos and interpretations to illustrate the geology of Druidston Haven, Pembrokeshire. The cliffs of Druidston Haven mostly consist of Ordovician (Caradocian) age shales with some thin sandstones. During the Caledonian orgogeny at the end of the Silurian period, these were deformed into a series of mostly upright open folds. These were then re-folded by Variscan movements at the end of Carboniferous, to become largely recumbent (near horizontal) or partly inverted, facing down towards the south. The Ordovician rocks form a horst - a ridge or block of strata faulted against younger rocks on either side. The Druidston Horst is bounded by the South Druidston Boundary Fault at the south end of the Haven, and the North Druidston Boundary Fault at the north end. This photo shows the southern end of the horst, terminated by the Southern Boundary Fault; a significant structure with a throw (displacement) of at least 1500 metres to the south, bringing Namurian 'Millstone Grit Series' (upper Carboniferous) rocks into contact with the Ordovician shales.

Disharmonic recumbent fold at Broad Haven - view along the fold crest . On the north headland of Broad Haven, Pembrokeshire, is this spectacular fold structure in Coal Measures strata. The fold is essentially an anticline strongly overturned northwards (to the left) so that its fold axis is near to horizontal. The relatively strong sandstone beds (orange-brown) have deformed into an angular chevron-shaped fold, while the softer seatearth below the coal has deformed into a rounded fold, seen in the lower part of the structure, almost from the camera viewpoint. This has been achieved by considerable slip along individual bedding planes and softer, incompetent, material has been squeezed into the hinge zones from the fold limbs. This has occurred particularly along the horizon of a thin coal seam and the immediately overlying dark shales, which have 'flowed' into the angular apex of the fold to the left of centre. The seatearth is also cut by a coarsely-developed axial planar cleavage, which is partly responsible for the 'nubbly' texture on the rounded part of the fold. The cleavage fans out almost radially, best seen in section on the rounded bed in the middle distance.

Disharmonic recumbent fold at Broad Haven - view of the hinge zone On the north headland of Broad Haven, Pembrokeshire, is this spectacular fold structure in Coal Measures strata. The fold is essentially an anticline strongly overturned northwards (to the left) so that its fold axis is near to horizontal. This photo shows a closer view of the hinge zone along the horizon of a thin coal seam and the immediately overlying dark shales, which have 'flowed' into the angular apex of the fold just to the left of centre. The relatively strong sandstone beds (orange-brown) have deformed into an angular chevron-shaped fold, while the softer grey seatearth below the coal has deformed into a rounded fold, seen in the lower part of the structure, to the right of centre. The seatearth is also cut by a coarsely-developed axial planar cleavage (better seen in the previous photo), which is partly responsible for the 'nubbly' texture on the rounded part of the fold.

Disharmonic recumbent fold at Broad Haven - general view . On the north headland of Broad Haven, Pembrokeshire, is this spectacular fold structure in Coal Measures strata. The fold is essentially an anticline strongly overturned northwards (to the left) so that its fold axis is near to horizontal. The fold is disharmonic - individual beds in the fold have become detached and are no longer concentric with each other, as can be seen above and to left of centre. This has been achieved by considerable slip along individual bedding planes and softer, incompetent, material has been squeezed into the hinge zones from the fold limbs.

The Stackpole Fault exposed in a small cove at Stackpole Quay, Pembrokeshire. The camera location of the previous photo in the photostream was in the notch at the top of the photo. Jan is standing just to the left of the fault plane, which consists of a jumbled smash-zone of fragmented limestone recemented with calcite. To the left of the fault plane, the rocks are dipping northwards at about 45°. There is a well-developed, nearly vertical set of fractures (parallel to Jan). These are axial planar cleavage developed around the Stackpole Quay anticline, but have probably been amplified as pinnate cleavage by the proximity and movement of the Stackpole Fault. (A bit like trying to plane a piece of wood against the grain - the plane 'chatters' and you get a rough surface, not a smooth one)

Cobbler's Hole is a steep rocky inlet on St Ann's Head in Pembrokeshire. It has almost vertical walls with the sea crashing in and out over 100 feet below. The star attraction of Cobbler's Hole is the splendid anticline and syncline fold couplet in the Devonian-age Milford Haven Group of the Old Red Sandstone rocks.

A nice, bright, blusterous morning in Pembrokeshire! Cobbler's Hole is a steep rocky inlet on St Ann's Head in Pembrokeshire. It has almost vertical walls with the sea crashing in and out over 100 feet below. The star attraction of Cobbler's Hole is the splendid anticline and syncline fold couplet in the Devonian-age Milford Haven Group of the Old Red Sandstone rocks. The 'space problem' in the core of the folds has been accommodated by minor thrusting. There is also a strong axial planar cleavage, particularly developed in the finer grained sediments. Skokholm and Skomer islands are visible in the distance.