Settle, Horton and Ribblehead

As the train pulls out of Settle, Sugar Loaf hill is to the east. It is formed of Carboniferous Limestone and along the bottom of the hill lies the South Craven fault. This fault is part of the system of faults (including the North Craven Fault) which form the boundary between the Pennine basin to the south and higher ground of the Askrigg block to the north. The fault continues across the railway following the line of hills to the northwest.

Horizontal limestone beds above sleeply dipping Ordovician rocks – Anthony Glossop

The valley sides between Settle and the Taitlands Tunnel are formed of the same Carboniferous Limestones as seen at Malham Cove and Goredale Scar to the east. Just north of the Taitlands Tunnel the line crosses the North Craven Fault and the railway runs across some of the older Silurian Austwick and Horton Formations. These are steeply dipping layers of sandstones and siltstones and can be seen as ridges of rocks in the river bed. They contain fossil graptolites (small marine creatures that lived in large colonies that floated in surface waters, sinking to the ocean bottom on death).

To the west, the hills are capped with near horizontal layers of Carboniferous Limestones, which lie unconformably (at a lower angle) to the older rocks beneath. This unconformity represents a long period of time, about 80 million years, in which the older rocks were uplifted, deformed and eroded, before the younger rocks were laid down. The unconformity is particularly clear in the Horton Quarries, with the younger rocks visible along the top of the quarry and the steeply dipping older rocks being quarried away beneath.

Where the valley widens out, the flat valley bottom is covered in glacial till and river sediments.

On eastern side of the railway Pen-y-Ghent comes into view. It is made up of layers of Carboniferous Limestone, capped by gritstones and sandstones (and a few thin coal seams) of the Millstone Grit.

Pen-y-ghent – Anthony Glossop

Just south of Horton station, the railway goes over the Ordovician Ingleton Group, the oldest rocks on the line. These are mainly hidden by glacial till, but a section can be seen in the cutting just before the station. These are steeply dipping green coloured siltstones and sandstones, which contain fossils of brachiopods (similar in appearance to clams, but unrelated), graptolites and trilobites (marine creatures looking a little like very large woodlice).

Past Horton Station, the landscape is dominated by the Carboniferous Limestones. These contain fossil corals, brachiopods and crinoids (similar to sea lilies). Many of the beds (layers) can be traced across the landscape. One particularly distinctive bed is composed of Girvanella – masses of tiny calcite tubes that formed around cyanobacteria (blue-green algae). Millstone Grit tops the taller hills, including Ingleborough and Whernside. The beds are roughly horizontal giving the three peaks their distinct flat tops and more resistant layers give the sides their stepped appearance.

The valleys and hills have been smoothed by the action of glaciers during the ice age. Many of the hills are coated in peat formed during the cold period after the last age.

• Introduction, Geological History and Economic Geology
• Settle, Horton and Ribblehead
• Ribblehead, Dent and Garsdale
• Garsdale, Kirkby Stephen and Appleby
• Appleby, Langwathby and Lazonby
• Lazonby, Armathwaite and Carlisle
• Geological Terms and References

						The longest (but not the highest - Smardale) viaduct is Ribblehead at 440 yards long and 105 feet at its highest point