The River Twiss is a river in the county of

Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other English counties, functions have ...

, England. The source of the river is Kingsdale Beck which rises at Kingsdale Head at the confluence of Back Gill and Long Gill in the

Yorkshire Dales The Yorkshire Dales is an upland area of the Pennines in the historic county of Yorkshire, England, most of it in the Yorkshire Dales National Park created in 1954. The Dales comprise river valleys and the hills rising from the Vale of York w ...

. Beneath Keld Head, it changes its name to the River Twiss. It has two notable waterfalls, Thornton Force and Pecca Falls, and its course follows part of the Ingleton Waterfalls Walk, then through Swilla Glen to Thornton in Lonsdale and down to Ingleton, where it meets the

River Doe The River Doe is a river in North Yorkshire, England. The river's source is near God's Bridge close to the settlement of Chapel-le-Dale and flows through Twisleton in a south-westerly direction to Ingleton, where it meets the River Twiss to f ...

to form the River Greta. The English landscape artist J. M. W. Turner was a frequent visitor to the area and his sketch of Thornton Force in 1816 is currently part of the Tate collection.

Course

From the caves below Keld Head there is a flow of water that joins Kingsdale Beck to form the River Twiss. It flows south over Thornton Force and Pecca Falls and through woodland to join the River Doe at Ingleton.

Waterfalls

The drop of Thornton Force is about . Pecca Falls has three drops totalling that fall into their own deep pools.

Geology

In its upper part the river runs through a valley cut into horizontal beds of Carboniferous Great Scar limestone. At Thornton Force it crosses a notable

unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...

into the underlying, steeply inclined

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

greywacke Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lit ...

s. The unconformity is clearly visible in the face of the waterfall. The Ordovician strata influence the character of the steep and narrow Swilla Glen and its waterfalls until, just north of Ingleton, the river crosses the Craven Fault and onto

Carboniferous Limestone Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian epoch (geology), Epoch of the Carboniferous period (geology), Period. T ...

once again.

Crossings

* Ravenray Bridge (foot) * Pecca Bridge (foot) * Manor Bridge (foot) * Unnamed Road, Ingleton

Gallery

Sources

Ordnance Survey Open Data https://www.ordnancesurvey.co.uk/business-government/tools-support/open-data-support

References

{{DEFAULTSORT:Twiss Rivers of North Yorkshire 2Twiss