The Norber erratics are one of the finest groups of

glacial erratic A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundred ...

boulders in Britain. They are found on the southern slopes of

Ingleborough Ingleborough () is the second-highest mountain in the Yorkshire Dales, England. It is one of the Yorkshire Three Peaks (the other two being Whernside and Pen-y-ghent), and is frequently climbed as part of the Three Peaks walk. A large part o ...

, close to the village of

Austwick Austwick is a village and civil parish in the Craven district of North Yorkshire, England, about north-west of Settle. The village is on the edge of the Yorkshire Dales National Park. Before local government reorganisation in 1974, Austwick ...

in the

Yorkshire Dales The Yorkshire Dales is an upland area of the Pennines in the Historic counties of England, 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 ri ...

. The

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grid reference of the boulder field is . The erratics are classic

geomorphological Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or n ...

features from the glaciation of northern England. In his chapter on the

Pennines The Pennines (), also known as the Pennine Chain or Pennine Hills, are a range of uplands running between three regions of Northern England: North West England on the west, North East England and Yorkshire and the Humber on the east. Commo ...

, A.E. Trueman wrote: "Particularly well known are the great perched blocks of dark grit which stand on the limestone platform at Norber near Settle." Many of the

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

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 ...

boulders at the site are perched on pedestals of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

up to 30cm high. The boulders were probably deposited by melting ice sheets at the end of the last ice age, around 12,000 years ago. The pedestals have developed because the erratic boulders have protected the underlying

from solution by rainfall, giving estimates of the rate of lowering of the surrounding

limestone pavement A limestone pavement is a natural karst landform consisting of a flat, incised surface of exposed limestone that resembles an artificial pavement. The term is mainly used in the UK and Ireland, where many of these landforms have developed dist ...

of around 25mm per 1000 years. Recent cosmogenic dating suggests that the boulders have been exposed for around 17,900 years.

References

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