Force Garth Quarry

Overview

An active whinstone (dolerite) quarry on the Great Whin Sill in Upper Teesdale, opened in 1932 and still producing 250,000-300,000 tonnes of roadstone a year, close to the High Force waterfall.

History

Force Garth Quarry opened in 1932 to work the Great Whin Sill -- a sheet of tholeiitic quartz-dolerite intruded around 295 million years ago, reaching its greatest known thickness of around 70 metres in Teesdale -- for roadstone. By the 1980s the quarry was operated by Hargreaves Quarries Ltd, per the British Geological Survey's own 1984 Directory of Mines & Quarries; the site's earlier operating history between 1932 and the 1980s could not be confirmed from any source checked. Ownership later passed to Cemex UK Operations Ltd, which by 2012 was seeking permission from Durham County Council to extend the quarry and extract a further 5.2 million tonnes over 15 years, against an estimated remaining reserve of around 18 million tonnes.

Geology

The quarry works the Great Whin Sill, a Permian-age (c.295 million years old) sheet of tholeiitic quartz-dolerite intruded into the surrounding Carboniferous rocks; in Teesdale the sill reaches its maximum known thickness of around 70 metres. The dolerite is locally known as whinstone, and where exposed nearby at the disused High Force Quarry it displays the rough columnar jointing characteristic of a cooling dolerite sheet.

Workings

Worked as a large open quarry through almost the full thickness of the Whin Sill for crushed roadstone.

What remains

A still-active, working quarry: a 2015 visitor described 'fab viewpoints from up the chutes and some awesome plant machinery', and noted having to plan a visit around the site's normal staffed operating hours.

Abandoned workings can be dangerous — unstable ground, uncapped shafts, flooding and bad air are common even where a site looks safe from the surface. This entry describes history and general location only; it is not an access guide.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Force Garth works the Great Whin Sill, a tholeiitic quartz-dolerite sheet intruded around 295 million years ago, reaching its greatest known thickness of around 70 metres in Teesdale. ¹
• Force Garth Quarry was operated by Hargreaves Quarries Ltd in the 1980s, per the BGS's 1984 Directory of Mines & Quarries. ²
• The quarry produces 250,000-300,000 tonnes of whinstone a year against an estimated 18 million tonnes of remaining reserves; current operator Cemex UK Operations Ltd sought permission in 2012 to extend extraction by a further 5.2 million tonnes over 15 years. ³
• A 2015 visitor described the site as active and well-staffed, with 'fab viewpoints from up the chutes and some awesome plant machinery'. ⁴

Sources

1. (secondary) The Great Whin Sill in Teesdale - High Force & High Force Quarry — Geology North
2. (primary) Force Garth Quarry — Durham Mining Museum
3. (secondary) Force Garth Quarry, Forest and Frith, County Durham — Mindat
4. (observational) Force Garth Quarry, Middleton-in-Teesdale, April 2015 — 28DaysLater

Record created: 29 August 2026 · Last researched: 29 August 2026