Fossil Grove, Glasgow: An ancient forest tale

A unique ‘grove’ of fossil tree stumps preserved as they stood in life, around 325 million years ago

Lycopod tree stumps and ripple marks in the Fossil Grove.

The Fossil Grove in Glasgow is the oldest museum in the world that was created specifically for geoconservation. It was erected in 1889, two years after the stumps and upper roots of eleven fossil trees were discovered in a quarry during road and landscaping work for the new Victoria park.

These remarkable tree remains are preserved where they grew 325 million years ago, within sedimentary rocks formed in the Carboniferous Period. They are Lepidodendron, a primitive kind of vascular plant. The exceptionally detailed preservation of the trees means that the nature of the soil in which they grew, the characteristics of the Carboniferous forest environment, and the processes responsible for their burial and preservation have all been established by scientists. The soil consisting of silt and mud, has been transformed into a layer of rock containing fossilised plant material. The spacing of the trees suggests that the forest was a lot less dense than modern coniferous forests, with approximately 4500 trees per square kilometre.

How did the trees come to be preserved so beautifully? Well, we now know that the forest was swamped by sediment during the flooding of a large river or delta system. This caused the death of the trees and the burial and then replacement of the wood, resulting in the preservation of the tree stumps as the detailed sandstone casts we see today.

Above the fossil-rich layers of sedimentary rock there is a layer of dolerite. This is an igneous rock, that was injected as molten magma into the existing sedimentary rock about 290 million years ago during the early Permian period. Up to 8 meters of this rock layer or ‘sill’ are exposed near the fossil house with several thinner tongues of the sill and ‘rafts’ of sedimentary rock that got caught up within it. The base of the sill is exposed in the lower part of the quarry, where you can see a thin chilled margin – an area where the hot magma cooled rapidly on contact with the surrounding rocks. It was the quarrying of this dolerite that lead to the discovery of the tree fossils in 1887.

The area of the fossil trees is protected in law as a Site of Special Scientific Interest. The building, which originally had a glazed roof and a walkway, is currently owned and operated by Glasgow City Council’s Land & Environmental Services Department. The Fossil Grove Trust is working with the Council on plans to upgrade the building and redevelop the visitor experience so people can continue to enjoy and marvel at these unique relics of a long-vanished environment.

Find out more
ALLISON, I. and WEBSTER, D.J. 2017 (in prep). Geological Excursion Guide to the Fossil Grove. Geological Society of Glasgow.
Information on the Geological Society of Glasgow’s website: https://www.geologyglasgow.org.uk/geoconservation/rigs/fossil-grove/

The Fossil House and Lycopod statue. Image: David Webster.

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