Arran Geopark

Location: Arran
the natural world

Hutton's Unconformity

A rock outcrop in the north of Arran (Newton Shore at Lochranza) changed the world's understanding of geology and the earth’s history. In 1787 James Hutton, now known as the 'father of modern geology', observed that the outcrop was composed of gently sloping red sandstone rock on top of steeply sloping layers of grey schist.

We now consider the schist to be around 550 million years old and the overlying sandstone to be some 200 million years younger. This great gap in the layers of the geological record is known as an 'unconformity’.

Hutton concluded that it had taken an unfathomably long time for such a formation to have been created- “no vestige of a beginning, no prospect of an end”. This was truly radical at a time when the world was considered to be only 6000 years old and when most of the scientific community considered all rocks and landforms to be relics of the biblical flood.

The rock outcrop is now known as ‘Hutton’s Unconformity’ and the location is easy to find as it is marked by an engraved sandstone block.

As told by the Arran Geopark

More information on visiting the area can be found here.