Join @ScottishGeologist on a breathtaking geological journey across the Isle of Lewis and Harris, where the landscape tells a story stretching back nearly 3 billion years. From the Lewisian gneiss, some of the oldest rocks in Europe, to stunning Atlantic beaches and towering Harris mountains, this tour reveals how Scotland’s Outer Hebrides became a geological wonderland.
🪨 The Lewisian Gneiss Complex
Walk across outcrops of Lewisian gneiss, formed over 3.2 billion years ago deep in Earth’s crust.
Learn how these rocks were altered by intense heat and pressure, creating their distinctive banded appearance.
Understand how these gneisses are fragments of Earth’s earliest continental crust, older than almost all life.
⛰️ The Mountains and minerals of Harris
Explore the dramatic Harris hills, where gneiss forms a rugged, rocky landscape shaped by glaciers.
See how later intrusions of granite and pegmatite veins cut through the gneiss, telling a story of deep magmatic activity.
Trace how these ancient foundations influence the island’s modern topography.
Analyse crystals such as tourmaline, mica and quartz in pegmatic form.
🏜️ The Uig and Stornoway Sandstones
Visit exposures of Torridonian-like sandstones, deposited around 1 billion years ago by ancient rivers and deserts.
Spot sedimentary structures like ripples and cross-bedding, frozen evidence of vanished landscapes.
⛰️ Structural Geology in the Gneiss
• Analyse how the Lewisian was deformed over billions of years, recording cycles of burial, heating, and uplift.
• Look at isoclinal folds, refolded folds, and shear fabrics, and discuss what they reveal about the pressures and directions of ancient tectonic forces.
• Learn how geologists unravel deformation histories by tracing cross-cutting relationships between different fold generations.
• Compare the structures in Lewisian gneiss to those found in modern mountain belts like the Himalayas.
🌍 The Outer Hebrides Fault Zone (OHFZ)
Explore one of Scotland’s most significant tectonic structures, stretching for more than 200 km along the Outer Hebrides.
Understand how this ancient fault marks the boundary between the Lewisian gneiss block and rocks further east.
Learn that the OHFZ was reactivated several times:
During the Proterozoic, when the Lewisian basement was fractured and sheared.
During the Caledonian Orogeny (~430 million years ago), when thrusts and folds developed as Scotland collided with North America and Greenland.
Even later, during the opening of the Atlantic, when dykes intruded along fault lines.
See spectacular mylonites and sheared rocks, where the gneiss has been ground and stretched by movement along the fault.
Discuss how this deep crustal fault connects Arran, the mainland, and the Outer Hebrides, showing how Scotland’s geology is linked across regions.
🌊 Glacial and Coastal Landscapes
Discover how the last Ice Age carved corries, valleys, and lochs across Lewis and Harris.
Walk along the Atlantic coast, where white-sand beaches like Luskentyre meet outcrops of ancient gneiss.
Observe how waves and weather continue to shape the coast today, creating sea stacks, cliffs, and machair grasslands.
🏛️ Geology and Culture
Learn how Lewisian gneiss was used in building crofts and stone walls across the islands.
Visit the Callanish Standing Stones, erected over 5,000 years ago, and discuss how the local geology provided both the material and the setting for this remarkable site.
Hear how geology influenced settlement, farming, and industry in the Outer Hebrides.
👣 Hands-On Exploration
Examine thin bands of different minerals in the gneiss and learn how to identify feldspar, quartz, and mica.
Sketch folded gneiss outcrops and glacial features in a field notebook.
Compare the Lewisian to modern geological analogues, such as the Canadian Shield.
Who Should Attend?
Geology enthusiasts wanting to see some of the oldest rocks in the world.
Nature lovers drawn to Harris’s mountains and Lewis’s sweeping beaches.
Anyone fascinated by the link between geology, history, and human culture.
No prior geology background is needed—just good walking shoes and a love of wild landscapes.
📍 Location: Isle of Lewis & Harris, Outer Hebrides
Pick up available from Glasgow, Inverness or meet us there.
🗓️ Dates: Friday 27th July to 29th July 2026
⏰ Duration: 2-4 days
🎟️ Price:
£395pp from Glasgow
£365pp from Inverness
£300pp meet us there
(guiding, ferry and transport included. Accommodation not included - please book accomodation within a 5 mile radius of Stornoway)
Luskentyre
Scarista
Rodel
Harris tweed
Isle of Harris distillery
Stornoway
Callinish stones
Alpaca cafe
Port of ness
Led by @ScottishGeologist, this tour offers the chance to stand on rocks nearly as old as the Earth itself, while surrounded by some of Scotland’s most spectacular scenery. From billion-year-old gneiss to Ice Age landscapes and ancient monuments, the Outer Hebrides bring together deep time, cultural history, and natural beauty in one unforgettable journey.
Book Your Lewis & Harris Geology Adventure Today!
Step into the deep past of Scotland—where some of the world’s oldest rocks meet the wild Atlantic shore.
Join @ScottishGeologist on a breathtaking geological journey across the Isle of Lewis and Harris, where the landscape tells a story stretching back nearly 3 billion years. From the Lewisian gneiss, some of the oldest rocks in Europe, to stunning Atlantic beaches and towering Harris mountains, this tour reveals how Scotland’s Outer Hebrides became a geological wonderland.
🪨 The Lewisian Gneiss Complex
Walk across outcrops of Lewisian gneiss, formed over 3.2 billion years ago deep in Earth’s crust.
Learn how these rocks were altered by intense heat and pressure, creating their distinctive banded appearance.
Understand how these gneisses are fragments of Earth’s earliest continental crust, older than almost all life.
⛰️ The Mountains and minerals of Harris
Explore the dramatic Harris hills, where gneiss forms a rugged, rocky landscape shaped by glaciers.
See how later intrusions of granite and pegmatite veins cut through the gneiss, telling a story of deep magmatic activity.
Trace how these ancient foundations influence the island’s modern topography.
Analyse crystals such as tourmaline, mica and quartz in pegmatic form.
🏜️ The Uig and Stornoway Sandstones
Visit exposures of Torridonian-like sandstones, deposited around 1 billion years ago by ancient rivers and deserts.
Spot sedimentary structures like ripples and cross-bedding, frozen evidence of vanished landscapes.
⛰️ Structural Geology in the Gneiss
• Analyse how the Lewisian was deformed over billions of years, recording cycles of burial, heating, and uplift.
• Look at isoclinal folds, refolded folds, and shear fabrics, and discuss what they reveal about the pressures and directions of ancient tectonic forces.
• Learn how geologists unravel deformation histories by tracing cross-cutting relationships between different fold generations.
• Compare the structures in Lewisian gneiss to those found in modern mountain belts like the Himalayas.
🌍 The Outer Hebrides Fault Zone (OHFZ)
Explore one of Scotland’s most significant tectonic structures, stretching for more than 200 km along the Outer Hebrides.
Understand how this ancient fault marks the boundary between the Lewisian gneiss block and rocks further east.
Learn that the OHFZ was reactivated several times:
During the Proterozoic, when the Lewisian basement was fractured and sheared.
During the Caledonian Orogeny (~430 million years ago), when thrusts and folds developed as Scotland collided with North America and Greenland.
Even later, during the opening of the Atlantic, when dykes intruded along fault lines.
See spectacular mylonites and sheared rocks, where the gneiss has been ground and stretched by movement along the fault.
Discuss how this deep crustal fault connects Arran, the mainland, and the Outer Hebrides, showing how Scotland’s geology is linked across regions.
🌊 Glacial and Coastal Landscapes
Discover how the last Ice Age carved corries, valleys, and lochs across Lewis and Harris.
Walk along the Atlantic coast, where white-sand beaches like Luskentyre meet outcrops of ancient gneiss.
Observe how waves and weather continue to shape the coast today, creating sea stacks, cliffs, and machair grasslands.
🏛️ Geology and Culture
Learn how Lewisian gneiss was used in building crofts and stone walls across the islands.
Visit the Callanish Standing Stones, erected over 5,000 years ago, and discuss how the local geology provided both the material and the setting for this remarkable site.
Hear how geology influenced settlement, farming, and industry in the Outer Hebrides.
👣 Hands-On Exploration
Examine thin bands of different minerals in the gneiss and learn how to identify feldspar, quartz, and mica.
Sketch folded gneiss outcrops and glacial features in a field notebook.
Compare the Lewisian to modern geological analogues, such as the Canadian Shield.
Who Should Attend?
Geology enthusiasts wanting to see some of the oldest rocks in the world.
Nature lovers drawn to Harris’s mountains and Lewis’s sweeping beaches.
Anyone fascinated by the link between geology, history, and human culture.
No prior geology background is needed—just good walking shoes and a love of wild landscapes.
📍 Location: Isle of Lewis & Harris, Outer Hebrides
Pick up available from Glasgow, Inverness or meet us there.
🗓️ Dates: Friday 27th July to 29th July 2026
⏰ Duration: 2-4 days
🎟️ Price:
£395pp from Glasgow
£365pp from Inverness
£300pp meet us there
(guiding, ferry and transport included. Accommodation not included - please book accomodation within a 5 mile radius of Stornoway)
Luskentyre
Scarista
Rodel
Harris tweed
Isle of Harris distillery
Stornoway
Callinish stones
Alpaca cafe
Port of ness
Led by @ScottishGeologist, this tour offers the chance to stand on rocks nearly as old as the Earth itself, while surrounded by some of Scotland’s most spectacular scenery. From billion-year-old gneiss to Ice Age landscapes and ancient monuments, the Outer Hebrides bring together deep time, cultural history, and natural beauty in one unforgettable journey.
Book Your Lewis & Harris Geology Adventure Today!
Step into the deep past of Scotland—where some of the world’s oldest rocks meet the wild Atlantic shore.
