Hugh Miller’s Birthplace Cottage & Museum

The Devonian period

If you were to travel back to the Devonian period, Scotland would look very different. All the continents were fused into two supercontinents: Laurasia along the equator and Gondwana close to the South Pole. Scotland was in the heart of Laurasia and neighboured Greenland, America and the rest of Europe. The iconic mountains that make the Scottish Highlands unique had only recently been formed, and Ben Nevis was taller than today’s Himalayas. Forget lush green fields or thick pine forests; Scotland was a harsh desert landscape with scant wildlife besides the occasional centipede or shrub. Whilst life on land was nothing exciting, life in the water was another matter.

During the Devonian period, Cromarty was underwater. Whilst most of Scotland was covered in desert, the very north was submerged beneath an enormous freshwater lake known as Lake Orcadie. Throughout the thousands of years this lake existed, it managed to stretch from the Moray Coast north to Orkney and perhaps even as far away as the west coast of Norway. The sediment deposited at the bottom of this lake would eventually become part of the Old Red Sandstone formation that Miller was famous for exploring.

The fossil fish

Some scientists have nicknamed the Devonian period the ‘Age of Fishes‘ because of the huge diversity of fish species that evolved during this period, some recognisable, and others alien to today’s fish. On Cromarty beach, four main groups of fossil fish are found, as detailed in the gallery below.

The end of the world

The Devonian period lasted for 60 million years, but it ended abruptly around 360 million years ago with a mass extinction event that killed around 80% of life on Earth. However, life on land does not seem to have been hit nearly as severely as life in water. The reason for this is unclear, but one popular theory among scientists is climate change. With life on land sparse of predators, plants gained a stronger foothold and removed enough carbon from Earth’s atmosphere that the planet’s climate changed, and freak weather events became more common. Nutrients from decaying, uneaten plants triggered colossal algal blooms, which blanketed the surface of rivers, lakes and seas. Once the algae died, it was broken down by bacteria, which took up so much oxygen from the water that everything else was suffocated. 95% of all aquatic backboned animals that lived during the Devonian period became extinct, including every placoderm.

Such events are not unique to Earth’s prehistory. Today, species biodiversity is falling rapidly due to climate change and chemical pollutants. The Trust is dedicated to fighting against the ongoing threat of human-induced climate change through various projects, both large and small, from woodland restoration on Mar Lodge Estate to ensuring our historic buildings are up to climate-friendly standards.

Studying the Old Red

As the sediments that formed the Old Red Sandstone were buried and cemented into rock, they captured the record of life in the Devonian period. Hundreds of millions of years later, these rocks were exposed to the surface and began to be explored by those with a keen eye.

The first person to begin studying the Old Red Sandstone was the geologist Sir Roderick Murchison from Muir of Ord, who started with the fossil fish from Caithness in the 1820s. Hugh Miller’s investigations were not far behind, beginning in the 1830s and continuing for the rest of his life. His discoveries and observations were written down, and his landmark book The Old Red Sandstone: or New Walks in an Old Field was published in 1841. He is considered one of Scotland’s most influential geologists, and his writing has helped popularise science among the masses.

Today, research into Scotland’s prehistoric past is still ongoing in Cromarty, spearheaded by palaeontologists from the University of Aberdeen. Hugh Miller’s Birthplace is a proud supporter of this ongoing research, allowing visitors to partake in citizen science and discover fossils on Cromarty beach. In 2024, we took over 150 people on fossil hunting walks and discovered 174 brand new fossil specimens, all of which went directly towards helping build on our understanding of life in ancient Scotland.