Turin Hill

Also within

Angus County

Condition (NatureScot)

Habitats

Fast flowing river and stream

Geology & landscape

Mining / Industrial: Quarry · Geological Period: Devonian, Silurian · Rock Type: Sandstone, Siltstone

Landscape processes: Fluvial, Volcanic / Igneous

Description

Turin Hill Turin Hill Site of Special Scientific Interest is located 6 km north-east of Forfar, and comprises five small abandoned quarries: (a) Aberlemno, (b) Tillywhandland, (c) Myrestone, (d) Pitscandly and (e) Wemyss. The site is important for its non-marine, Devonian age rock sequence, and for three distinct groups of fossils that are found in the rocks: fossil fish (chordata), fossil arthropods, and fossil plants. Non-marine Devonian Aberlemno Quarry The contact between the Dundee Flagstone Formation and the overlying Scone Sandstone Formation, both of the Lower Devonian age Arbuthnott-Garvock Group (416-407 million years old), is exposed in a sequence of remarkably laterally persistent beds. The Dundee Flagstone Formation includes sandstones deposited by rivers and mudstones formed from sediment deposited in a shallow lake environment. The mudstones contain important fish and plant fossils. The cross-bedded sandstones of the overlying Scone Sandstone Formation marks significant palaeoenvironmental change from a lake to a braided river. Tillywhandland Quarry This quarry site provides a reference section for the Dundee Flagstone Formation, and is unique in the Midland Valley in exposing a clastic-carbonate-organic laminite similar to those found in the Mid-Devonian Orcadian Basin. The 1.3 m of fish-bearing laminite comprises a repeated ~5mm thick sequence of clastic siltstone, carbonate, organic matter, and green claystone. It represents about 2000 years of lake-sediment deposition in ‘Lake Forfar’. A 60 mm-thick layer of pale green to buff bentonitic clay (formed from the breakdown of volcanic ash and tuff), 1m above the base of the laminite, is evidence of contemporaneous volcanic activity and is an important marker horizon. Silurian - Devonian Chordata (Fossil Fish) Aberlemno Quarry This site exposes the highest fish bed of the Dundee Formation of the Arbuthnott- Garvock Group (Lower Devonian age) in the Forfar area. In the past cephalaspids have been found commonly at Aberlemno, whilst acanthodians occurred at the stratigraphically lower Tillywhandland site. ‘Turin Hill’ is given as the type locality for Cephalaspis pagei Lankester, a species abundant and well preserved at Aberlemno, which was the most prolific site for this widely known species in the Lower Old Red Sandstone of Scotland. Turinea pagei Powrie is also found here, at its type locality. Turinea, a thelodont, is common and widespread in Europe where it is used for correlation. There it only occurs as isolated denticles. Articulated specimens are extremely rare, and Aberlemno is the only specified site where complete specimens occur. It is one of Britain’s most important agnathan localities. Tillywhandland Quarry Tillywhandland Quarry exposes a thick sequence of Dundee Flagstone Formation sandstones, siltstones and mudstones. Within this is a fish bed of laminated shales yielding species of acanthodians of Dittonian aspect. It is the last remaining site yielding a large suite of Lower Devonian acanthodians at the historic type “locality” of Turin Hill. Four species have been demonstrably attributed to Tillywhandland as their type locality: Euthacanthus grandis Powrie, Euthacanthus macnicoli Powrie, Parexus falcatus Powrie, and Vernicomacanthus uncinatus Powrie. An outstanding site for its fish faunas, the only extant locality to yield such faunas at Turin Hill and the probable type locality for numerous species. Arthropoda (excluding insects and trilobites) Turin Hill (Aberlemno, Myrestone, Pitscandly and Wemyss) The Lower Devonian age eurypterid fauna from Forfar is internationally renowned. It has yielded eight eurypterid species, including the type specimens for five of these. The giant Pterygotus anglicus, pride of collections in our national museums, occurs here together with a unique fauna of stylonuroid eurypterids. The taxonomy and functional morphology of these forms was described in great detail by Waterston, providing a considerable proportion of our knowledge of these extinct animals. Additionally, rare millipede and kampecarid myriapods occur here as well as the eurypterid Erieopterus, a genus otherwise associated with North America. Palaeozoic Palaeobotany Turin Hill Quarries (Aberlemno, Pitscandly and Wemyss) This quarry complex is of national importance for the fossil plants within the Lower Devonian age Arbuthnott-Garvock Group. Rocks of this group here yield the most abundant assemblage of this Devonian, Pragian age (411-407 million years old) flora in Britain. The flora is dominated by Parka and Zosterophyllum with subsidiary Pachytheca, Prototaxites and Cooksonia and is distinct from the assemblage of the slightly younger Strathmore Group. This is the best example of this distinctive flora, typical of the Lower Devonian of the Scottish Midland Valley, which has correlatives in Spitzbergen and Russia.

Plant communities