CITATION ACHANARRAS QUARRY SITE OF SPECIAL SCIENTIFIC INTEREST Highland (Caithness) Site code: 13

NATIONAL GRID REFERENCE: ND 149544

OS 1:50,000 SHEET NO: Landranger Series 11 1:25,000 SHEET NO: Explorer Series 451

AREA: 39.71 hectares

NOTIFIED NATURAL FEATURES

Geological: Stratigraphy : Non-marine Devonian Palaeontology : Silurian - Devonian Chordata

DESCRIPTION

Achanarras Quarry Site of Special Scientific Interest (SSSI) is situated 2km west of the village of Spittal, Caithness. The rocks of the site were laid down in the middle stages of the Devonian period (398-385 million years ago) in a large inland basin known as the ‘Orcadian basin’ stretching from present day Shetland and Orkney to the Moray Firth. For long periods a lake existed in this basin (Lake Orcadie) but it frequently varied in size. Achanarras Quarry is a site of international importance due to the number and variety of well-preserved fossil fish that have been found.

Non-marine Devonian (rocks that surround the fossil fish) The site contains a rare exposure of the Middle Devonian ‘Achanarras Limestone Member’ and its contacts with the ‘Upper Caithness Flagstone Group’ above and ‘Lower Caithness Flagstone Group’ below. The Achanarras Limestone Member is a valuable stratigraphic marker bed that can be correlated with other limestone outcrops throughout the Orcadian basin. The rocks of the site record the transgression (deepening) and later regression (shallowing) of a lake environment in this area of the Orcadian Basin.

Silurian – Devonian Chordata (fossil fish) The fossils at Achanarras are found in a distinct layer of rock called the “Achanarras Fish Bed” within the Achanarras Limestone Member. This fish bed was deposited within Lake Orcadie about 392 million years ago during the middle stages of the Devonian geological period.

There are at least sixteen, well preserved species of fossil fish known to be present at Achanarras. More species of Devonian fossil fish are found here than anywhere else in Scotland and it is perhaps the richest fossil fish site of its age in Britain. Achanarras Quarry is the “type locality” for two species of fish, Rhamphodopsis threiplandi Watson and Palaeospondylus gunni Traquair, which means that the species were first found and identified at this site. Other specimens of particular interest include an Actinolepis fossil fish, the first record for this species in Scotland,

and a Chasmataspid (an animal related to the horseshoe crab). It is likely that the quarry will continue to yield fossil specimens new to science.

NOTIFICATION HISTORY

First notified under the 1949 Act: 1962, 1975 Re-notified under the 1981 Act: 13 June 1986 with a 43 ha reduction in area Partial denotification confirmed: 29 October 2010 with a 1.2 ha reduction in area Notification reviewed under the 2004 Act: 29 October 2010 and 29 March 2016 (citation only)

REMARKS

Area of site reduced (from 41.7 ha)