Drilling into Great Glen Fault reveals glimpse into ancient geological history

Geologists are gaining a unique insight into the geological history of Scotland through the analysis of core rock extracted from the Great Glen Fault. This fault is an extensive, 1,000km-long and 40km-deep geological structure that runs from Ireland through Scotland to Norway. While the fault zone occasionally experiences tremors and minor earthquakes, the majority of the associated rocks are hidden beneath the waters of Loch Ness, Loch Oich, and Loch Lochy.

The core rock was drilled as part of investigations for a proposed hydro-storage scheme by SSE Renewables at the Coire Glas site near Loch Lochy. Scientists from the British Geological Survey (BGS) are studying 10 meters of rocks from the fault zone, obtained from depths of 30-40 meters. These rocks provide valuable insights into how fault systems operate and how fluids from deep within the Earth impact rock properties, offering a glimpse into the distant past.

Geologist Romesh Palamakumbura highlighted the historical significance of the fault zone, which originally formed around 400 million years ago during the initial shaping of Scotland. He noted that the fault has undergone reactivation during various geological periods, such as the Carboniferous era 300 million years ago and the opening of the North Atlantic. This analysis contributes to a broader understanding of the geological history of northern Scotland and the activity and evolution of fault systems over time.

The core rock was obtained in 2023 and has been under analysis at the BGS in Edinburgh since the end of 2024. Palamakumbura expressed his excitement at having the opportunity to study such remarkable and rare geological specimens. The core’s storage at BGS ensures accessibility for the scientific community, preserving these rocks for future research and generations to come.

Further bore holes have been drilled at the Coire Glas site, with depths reaching approximately 650 meters. Additional segments of the core rock are anticipated to be recovered in the future, providing more insights into geological processes and fault systems. BGS emphasized the core’s potential to address fundamental geological questions, enhance understanding of major faults in seismically active areas, and contribute to renewable energy and infrastructure projects.

SSE Renewables commended the scientific contributions resulting from the core rock recovery, stating that it has advanced the understanding of the Great Glen Fault and similar geological structures globally. Beyond its scientific value, the recovered core has been crucial for evaluating ground conditions and mitigating risks in the Coire Glas project development. The collaboration between BGS and SSE Renewables underscores the importance of interdisciplinary efforts in advancing geological knowledge and sustainable infrastructure development.