Aire Gap
Encyclopedia
Aire Gap is a mountain pass through the backbone of England
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...

 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.

Aire Gap as a geological division

Geologically the Aire Gap lies between the Craven Fault
Craven Fault
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 limestone uplands 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...

 to the north and the Forest of Bowland
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 moors 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 South Pennines being the system between the Aire Gap and the Peak [District].
It was formed by the dropping of the Craven Fault
Craven Fault
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...

s in the Carboniferous
Carboniferous
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"...

 through Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 periods combined with glacial scouring of the ice sheets in the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

.
The Aire Gap completes its grand function of splitting the pennines into north and south by allying with the Ribble. The Pennine chain is divided into two sections by the Aire Gap formed by the river Aire flowing south, a member of the Humber basin, and the Ribble flowing west and entering the Irish sea.

Aire Gap as a route

The Pennines form a natural barrier to east-west communications, but there are the Tyne Gap linking Carlisle and Newcastle and the Aire Gap linking Lancashire and Yorkshire.

Its extent is vague, a 19th century author wrote: However Skipton
Skipton
Skipton is a market town and civil parish within the Craven district of North Yorkshire, England. It is located along the course of both the Leeds and Liverpool Canal and the River Aire, on the south side of the Yorkshire Dales, northwest of Bradford and west of York...

 is now considered more central to the Aire Gap than terminal.

The Aire Gap has been of considerable strategic importance in days gone by, with the castle at Skipton
Skipton
Skipton is a market town and civil parish within the Craven district of North Yorkshire, England. It is located along the course of both the Leeds and Liverpool Canal and the River Aire, on the south side of the Yorkshire Dales, northwest of Bradford and west of York...

 overseeing the general area

Aire Gap as Single Point Location

The term is used in Ribblesdale and Pendle to denotes a hypsograph between itself and Airedale.
  • Ribblesdale’s Aire Gap designates a precise point at 160 m (525 ft) just East of Hellifield
    Hellifield
    Hellifield is a village and civil parish in the Craven district of North Yorkshire, England . The village once was an important railway junction on the Settle-Carlisle Railway between the Midland Railway and the Lancashire and Yorkshire Railway, but Hellifield railway station is now a shadow of...

     at 54.00000°N 2.16667°W a point labeled Aire Gap on Bing maps. Virtualtenby write "Aire Gap - a gap located 6.1 Miles away from Skipton's centre, is a low place in a ridge, not used for transportation" In fact it is a field inbetween the railway and the A65. The point is the watershed of that pass.
  • The head of Pendle Water
    Pendle Water
    Pendle Water is a minor river in Lancashire.Rising on Pendle Hill, Pendle Water cuts a deep valley between Barley Moor and Spence Hill, where it feeds the two Ogden Reservoirs, before making its way eastward through Roughlee, collecting Blacko Water, draining the valley near Wheathead, at Water...

     valley culminates in Foulridge 53.8768°N 2.176420°W near where Colne
    Colne
    Colne is the second largest town and civil parish in the Borough of Pendle in Lancashire, England, with a population of 20,118. It lies at the eastern end of the M65, 6 miles north-east of Burnley, with Nelson immediately adjacent, in the Aire Gap with two main roads leading into the Yorkshire...

     commonly describes itself as being in the Aire Gap When the Leeds and Liverpool Canal
    Leeds and Liverpool Canal
    The Leeds and Liverpool Canal is a canal in Northern England, linking the cities of Leeds and Liverpool. Over a distance of , it crosses the Pennines, and includes 91 locks on the main line...

     was being dug they planned to route via Hellifield but changes in industry made them take a short cut over Foulridge. This new gap was manufactured by digging a tunnel at altitude 140 m (459 ft) under of Foulridge’s 165 m (541 ft) to make a route even lower than the 160m pass near Hellifield.

Topography

The treeless moorland gives no shelter from storms. Even modern Pennine transport can find it a formidable barrier for roads can be blocked by snow for several days. But the Aire Gap route is a welcoming sheltered passageway, and also inhabited along its length.
The Aire Gap was of great topographic
Topography
Topography is the study of Earth's surface shape and features or those ofplanets, moons, and asteroids...

 significance for the historic North of England for it provides a low-altitude pass
Mountain pass
A mountain pass is a route through a mountain range or over a ridge. If following the lowest possible route, a pass is locally the highest point on that route...

 through "the backbone of England"
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...

. It was the Pennine transport corridor from Cumbria
Cumbria
Cumbria , is a non-metropolitan county in North West England. The county and Cumbria County Council, its local authority, came into existence in 1974 after the passage of the Local Government Act 1972. Cumbria's largest settlement and county town is Carlisle. It consists of six districts, and in...

 and Strathclyde
Kingdom of Strathclyde
Strathclyde , originally Brythonic Ystrad Clud, was one of the early medieval kingdoms of the celtic people called the Britons in the Hen Ogledd, the Brythonic-speaking parts of what is now southern Scotland and northern England. The kingdom developed during the post-Roman period...

 to the Vale of York
Vale of York
The Vale of York is an area of flat land in the north-east of England. The vale is a major agricultural area and serves as the main north-south transport corridor for northern England....

. Even Neolithic
Neolithic
The Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BC in some parts of the Middle East, and later in other parts of the world. It is traditionally considered as the last part of the Stone Age...

 long-distance trade is proved by many finds of stone axes from central Cumbria
Langdale axe industry
The Langdale axe industry is the name given by archaeologists to the centre of a specialised stone tool manufacturing at Great Langdale in England's Lake District during the Neolithic period .The area has outcrops of fine-grained greenstone suitable for making polished axes which have been...

.

To the Aire Gap’s north stand limestone
Carboniferous limestone
Carboniferous Limestone is a term used to describe a variety of different types of limestone occurring widely across Great Britain and Ireland which were deposited during the Dinantian epoch of the Carboniferous period. They were formed between 363 and 325 million years ago...

 mountains of up to 736 m (2,415 ft) above mean sea level
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

 and to its south lie bleak sandstone
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...

 moors, that above 275 m (902 ft) grow little but bracken.

The builders of the "Little" North Western Railway sought the lowest course through the Aire Gap and found that to be 166 m (545 ft) near 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 at 54.074167°N 2.318056°W, and 160 m (525 ft) just East of Hellifield
Hellifield
Hellifield is a village and civil parish in the Craven district of North Yorkshire, England . The village once was an important railway junction on the Settle-Carlisle Railway between the Midland Railway and the Lancashire and Yorkshire Railway, but Hellifield railway station is now a shadow of...

 at 54.00000°N 2.16667°W a point labeled Aire Gap on maps.

The nearest alternative pass through the Pennines is Stainmore Gap (Eden-Tees) to the North, but that is not in Craven’s league for it climbs to 409 m (1,342 ft) and its climate is classed as sub-arctic in places. The nearest low-level routes across the country are the 228 m (748 ft) Tyne Gap
River Tyne
The River Tyne is a river in North East England in Great Britain. It is formed by the confluence of two rivers: the North Tyne and the South Tyne. These two rivers converge at Warden Rock near Hexham in Northumberland at a place dubbed 'The Meeting of the Waters'.The North Tyne rises on the...

 over 100 km (62 mi) to the north, or the Midlands just as far to the south.
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