Editing Craven Fault Zone — Malham to Settle - an excursion

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=== Locality 11, Great Scar viewpoint [SD 866 639] ===
 
=== Locality 11, Great Scar viewpoint [SD 866 639] ===
  
Continue westwards for some 400 m. The slopes and gullies to the northwest display the stratigraphy of the lower part of the Wensleydale Group (formerly called the Yoredales). This succession represents a continuation of shelf carbonate deposition, but with periodic interruption by mudstones in this area, but mudstones and sandstones (some with coals) north of the NCF. These siliciclastics were deposited during the southward progradation of a deltaic complex.
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Continue westwards for some 400 m. The slopes and gullies to the northwest display the stratigraphy of the lower part of the Wensleydale Group (formerly called the Yoredales). This succession represents a continuation of shelf carbonate deposition, but with periodic interruption by mud-stones in this area, but mudstones and sandstones (some with coals) north of the NCF. These siliciclastics were deposited during the southward progradation of a deltaic complex.
  
Compared with the underlying Malham Formation, the Wensleydale Group limestones are typically darker grey and contain more visually conspicuous fossils (particularly crinoids, corals, brachiopods and algae). The Wensleydale Group section exposed in the Great Scar escarpment includes, in ascending order, the Hawes Limestone (27 m), Gayle Limestone (16 m) and Hardraw Scar Limestone (14 m); the latter forming the skyline. The stepped topography is controlled by the mudstone bands separating the limestones. The top of the Lower Hawes Limestone contains several prominent fossil markers including algal (oncolite) beds ''('Girvanella'' Band'), a ''Gigantoproductus'' brachiopod bed, and a coral biostrome dominated by colonies of ''Siphonodendron'' and ''Lithostrotion.''
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Compared with the underlying Malham Formation, the Wensleydale Group limestones are typically darker grey and contain more visually conspicuous fossils (particularly crinoids, corals, brachiopods and algae). The Wensleydale Group section exposed in the Great Scar escarpment includes, in ascending order, the Hawes Limestone (27 m), Gayle Limestone (t6 m) and Hardraw Scar Limestone (14. m); the latter forming the skyline. The stepped topography is controlled by the mudstone bands separating the limestones. The top of the Lower Hawes Limestone contains several prominent fossil markers including algal (oncolite) beds ''('Girvanella'' Band'), a ''Gigantoproductus'' brachiopod bed, and a coral biostrome dominated by colonies of ''Siphonodendron'' and ''Lithostrotion.''
  
 
=== Locality 12, Stockdale viewpoint [SD 863 639] ===
 
=== Locality 12, Stockdale viewpoint [SD 863 639] ===
  
Follow the footpath to the head of Stockdale. The Gordale Limestone produces continuous scars in the footwall fault scarp of the MCF. The position of the contact with the underlying Cove Limestone Member, on the top of the lowest scar-former, is clearly discernible and analogous to that at Malham. Northwest-trending fractures of little throw have influenced erosion, producing nicks in the escarpment. The MCF runs south of the whale-back ridge in the valley bottom. The ridge is defined to the north by the more northerly of two westerly-diverging fractures which here characterize the MCF; the other fracture, with most of the throw, occurs some 100 m to the south, concealed by Bowland Shales.
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Follow the footpath to the head of Stockdale. The Gordale Limestone produces continuous scars in the footwall fault scarp of the MCF. The position of the contact with the underlying Cove Limestone Member, on the top of the lowest scar-former, is cleary discernible and analogous to that at Malham. Northwest-trending fractures of little throw have influenced erosion, producing nicks in the escarpment. The MCF runs south of the whale-back ridge in the valley bottom. The ridge is defined to the north by the more northerly of two westerly-diverging fractures which here characterize the MCF; the other fracture, with most of the throw, occurs some ioo m to the south, concealed by Bowland Shales.
  
High South Bank, south of the main valley, is an inlier of Dinantian limestones forming a northward-dipping hanging wall dip-slope. This inlier is analogous to that at Malham, and is almost certainly fault-defined on its eastern and western margins. Bowland Shales are banked against the limestone. Prior to burial by these mudstones, the limestone of this hanging wall block had undergone significant erosion. A small outcrop of 'reef' limestones forms the southernmost part of the inlier (on the skyline), while the main dip-slope (locally dipping up to 30°) is formed of Malham Formation and Wensleydale Group. The latter includes the Hawes to Hardraw Scar limestones, but these have been attenuated to a 5 m interval, and contain conglomeratic units. Quarries on the northern end of the inlier expose cross-bedded grainstones, correlatives of the Middle Limestone (Brigantian) of Fountains Fell. Small mineral workings occur in the Wensleydale Group limestones, with galena, malachite and baryte in the spoils, while a large area of quartz-rock has replaced the Malham Formation. Attenuation of the early Wensleydale Group limestones and succeeding erosion of the shelf margin, suggests a slight compressional regime on the previously extensional fault line (a process known as fault inversion) before collapse of the hanging wall into a series of downthrown fault-blocks in late Dinantian times. The subsidiary faults (mostly northwest-trending) both north and south of the MCF were formed at this time, and reflect a component of right-lateral movement on the Craven fault system.
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High South Bank, south of the main valley, is an inlier of Dinantian limestones forming a northward-dipping hanging wall dip-slope. This inlier is analogous to that at Malham, and is almost certainly fault-defined on its eastern and western margins. Bowland Shales are banked against the limestone. Prior to burial by these mudstones, the limestone of this hanging wall block had undergone significant erosion. A small outcrop of 'reef' limestones forms the southernmost part of the inlier (on the skyline), while the main dip-slope (locally dipping up to 30°) is formed of Malham Formation and Wensleydale Group. The latter includes the Hawes to Hardraw Scar limestones, but these have been attenuated to a 5 m interval, and contain conglomeratic units. Quarries on the northern end of the inlier expose cross-bedded grainstones, correlatives of the Middle Limestone (Brigantian) of Fountains Fell. Small mineral workings occur in the Wensleydale Group limestones, with galena, malachite and baryte in the spoils, while a large area of quartz-rock has replaced the Malham Formation. Attenuation of the early Wensleydale Group limestones and succeeding erosion of the shelf margin, suggests a slight compressional regime on the previously extensional fault line (a process known as fault inversion) before collapse of the hanging wall into a series of downthrown fault-blocks in late Dinantian times. The subsidiary faults (mostly northwest-trending) both north and south of the MCF were formed at this time, and reflect a component of right-lateral movement on the Craven fault system.
  
 
=== Locality 13, Stockdale Lane corner [SD 848 638] ===
 
=== Locality 13, Stockdale Lane corner [SD 848 638] ===

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