Finding fault with Great Glen theory

Loch Ness is located in the Great Glen

The Scottish Highlands is coming under the microscope as geologists attempt to establish how Scotland's Great Glen was formed.

Experts at St Andrews University are heading an international project which will study the fracture in the earth's crust which cuts across the Highlands.

Some geoscientists believe the rocks on either side of the fault have different histories and come from different ages.

The study of Scotland's geology is important because it is a natural field laboratory in which to study how the Earth's crust has evolved

Dr Grahame Oliver

But the study co-ordinated by Dr Grahame Oliver of the university's School of Geography and Geosciences will aim to challenge that theory.

He is seeking to prove that each side of the fault has a similar geological history.

The Great Glen divides the north of Scotland from Fort William to Inverness, running along a line which takes in Loch Lochy, Loch Oich and Loch Ness.

The study, which is backed by the Carnegie Trust, will reconstruct the land on either side of the fault.

Scotland is made up of small pieces, or terranes, of the Earth's crust, which have been assembled and broken at various times over the last three billion years.

Experts from St Andrews University are involved

Dr Oliver said: "The study of Scotland's geology is important because it is a natural field laboratory in which to study how the Earth's crust has evolved.

"Many modern theories about Earth processes were initiated in Scotland."

By studying rock samples containing garnet and zircon from the Highlands, the team is aiming to determine their age and the conditions in which they were formed.

They will compare their samples with similar rocks from Canada, Greenland and Scandinavia before they can draw conclusions about their true origins.

The group aims to have a clear idea about whether its hypothesis can be proved by 2003.

Dating techniques

The project involves colleagues at the Crustal Geodynamics Group at St Andrews and fellow geologists and geoscientists in Glasgow, Inverness, Nottingham and Munich.

The rocks are being prepared by technicians at the St Andrews laboratory before being sent to NERC Isotope Geoscience Labs in Nottingham and the Institute for Mineralogy, Petrology and Geochemistry in Germany for isotopic age dating.

Experts will use techniques which can date rocks over 1,000 million years old with a margin of error of just 1%.