Craven Fault
Encyclopedia
The Craven Fault is the name applied by geologists to the group of crustal
faults in the Pennines
that form the south edge of the Askrigg Block
. It is evident at the surface in the contrast of limestone
with millstone grit
. It is coincident with the south edge of the Yorkshire Dales
National Park and the north edge of the Bowland Fells. It is the formative event of the Craven Basin and also of the upper part of the Aire Gap
.
at 54.190507°N 2.527339°W then branching three ways:
, through inhospitable highlands. This broad trough
separates the limestone Yorkshire Dales
from the Bowland Fells
and the Millstone Grit
plateaux of the South Pennines
. The Craven Basin coincides with most of the civic District of Craven
.
times and marks the southern limit of the Askrigg Block. However the North and South Faults continued to be active into post-Triassic
times. The Great Scar Limestone is exposed along the Middle Craven Fault at Malham Cove
, Gordale Scar
and along the South Craven Fault at Giggleswick
Scar.
was over 300 metres thick before weathering
.
The vertical throw of the fault zone is up to 1800 m (5,906 ft).
Charles Darwin
used the Craven Fault to illustrate how nature can so well conceal dramatic events: "The Craven Fault, for instance, extends for upwards of 30 miles, and along this line the vertical displacement of strata has varied from 600 to 3000 feet" but due to erosion
of surface features comparatively little of that height-difference remains evident.
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
faults in the Pennines
Pennines
The Pennines are a low-rising mountain range, separating the North West of England from Yorkshire and the North East.Often described as the "backbone of England", they form a more-or-less continuous range stretching from the Peak District in Derbyshire, around the northern and eastern edges of...
that form the south edge of the Askrigg Block
Askrigg Block
The Askrigg Block is the name applied by geologists to the crustal block forming a part of The Pennines of northern England and which is essentially coincident with the Yorkshire Dales. It is defined by the Dent Fault to the west and the Craven Fault System to the south whilst to the north it is...
. It is evident at the surface in the contrast of limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
with millstone grit
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
. It is coincident with the south edge of the Yorkshire Dales
Yorkshire Dales
The Yorkshire Dales is the name given to an upland area in Northern England.The area lies within the historic county boundaries of Yorkshire, though it spans the ceremonial counties of North Yorkshire, West Yorkshire and Cumbria...
National Park and the north edge of the Bowland Fells. It is the formative event of the Craven Basin and also of the upper part of the Aire Gap
Aire Gap
Aire Gap is a mountain pass through the backbone of England formed by geologic faults and carved out by glaciers. The term is used in various senses: a vast geological division, a travel route, or a location that is an entry into the Aire river valley....
.
Location
The Craven Faults are major cracks across the Pennines that reformed the North of England dramatically. These faults constitute a zone crossing the backbone of England from west to east commencing near Leck, LancashireLeck, Lancashire
Leck is a civil parish in the English county of Lancashire. The parish of Leck had a population of 189 recorded in the 2001 census, It is on the River Leck close to the main A65, south east of the Cumbrian town of Kirkby Lonsdale...
at 54.190507°N 2.527339°W then branching three ways:
- The North Craven Fault extends about 50 kilometres (31.1 mi) to 54.074°N 1.800°W.
- The Mid Craven Fault extends about 36 kilometres (22.4 mi) to 54.070°N 2.075°W.
- The South Craven Fault extends about 39 kilometres (24.2 mi) to 54.066°N 2.042°W.
Craven Basin
The Craven Faults form a low-altitude pass, also called the Aire GapAire Gap
Aire Gap is a mountain pass through the backbone of England formed by geologic faults and carved out by glaciers. The term is used in various senses: a vast geological division, a travel route, or a location that is an entry into the Aire river valley....
, through inhospitable highlands. This broad trough
Trough (geology)
In geology, a trough generally refers to a linear structural depression that extends laterally over a distance, while being less steep than a trench.A trough can be a narrow basin or a geologic rift....
separates the limestone Yorkshire Dales
Yorkshire Dales
The Yorkshire Dales is the name given to an upland area in Northern England.The area lies within the historic county boundaries of Yorkshire, though it spans the ceremonial counties of North Yorkshire, West Yorkshire and Cumbria...
from the Bowland Fells
Forest of Bowland
The Forest of Bowland, also known as the Bowland Fells, is an area of barren gritstone fells, deep valleys and peat moorland, mostly in north-east Lancashire, England. A small part lies in North Yorkshire, and much of the area was historically part of the West Riding of Yorkshire...
and the Millstone Grit
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
plateaux of the South Pennines
South Pennines
South Pennines is a region of moorland and hill country in northern England lying towards the southern end of the Pennines. It is bounded to the west by the Forest of Rossendale and the Yorkshire Dales to the north...
. The Craven Basin coincides with most of the civic District of Craven
Craven
Craven is a local government district in North Yorkshire, England that came into being in 1974, centred on the market town of Skipton. In the changes to British local government of that year this district was formed as the merger of Skipton urban district, Settle Rural District and most of Skipton...
.
Geological age
The Fault group comprises the North Craven Fault, Middle Craven Fault and South Craven Fault. The Middle Craven Fault moved mainly during CarboniferousCarboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
times and marks the southern limit of the Askrigg Block. However the North and South Faults continued to be active into post-Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
times. The Great Scar Limestone is exposed along the Middle Craven Fault at Malham Cove
Malham Cove
Malham Cove is a natural limestone formation 1 km north of the village of Malham, North Yorkshire, England. A well-known beauty spot, it is a large, curved limestone cliff at the head of a valley, with a fine area of limestone pavement at the top....
, Gordale Scar
Gordale Scar
Gordale Scar is a dramatic limestone ravine 1 mile or 1.5 km NE of Malham, North Yorkshire, England. It contains two waterfalls and has overhanging limestone cliffs over 100 metres high. The gorge was formed by water from melting glaciers...
and along the South Craven Fault at Giggleswick
Giggleswick
Giggleswick is a village and civil parish in the Craven district of North Yorkshire, England near the town of Settle. It is the site of Giggleswick School.-Origin of name:A Dictionary of British Place Names contains the entry:...
Scar.
Erosion
The Great Scar Limestone is over 200 metres thick and the overlying Yoredale SeriesYoredale Series
The Yoredale Series, in geology, is a local phase of the lower Carboniferous rocks of the north of England. The name was introduced by J. Phillips on account of the typical development of the phase in Yoredale , Yorkshire....
was over 300 metres thick before weathering
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...
.
The vertical throw of the fault zone is up to 1800 m (5,906 ft).
Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
used the Craven Fault to illustrate how nature can so well conceal dramatic events: "The Craven Fault, for instance, extends for upwards of 30 miles, and along this line the vertical displacement of strata has varied from 600 to 3000 feet" but due to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
of surface features comparatively little of that height-difference remains evident.