Ree Burn and Glenbuck Loch

Also within

Ayrshire and Arran CountyLanarkshire County

Condition (NatureScot)

Geology & landscape

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

Landscape processes: Fluvial

Description

Ree Burn and Glenbuck Loch Ree burn and Glenbuck Loch lying just over six kilometres east of Muirkirk is of special palaeoenvironmental and palaeontological significance demonstrating changes which occurred at the time of the closure of the lapetus ocean. The site is one of the most geologically important Silurian inliers in the Midland Valley and shows the important transition from a fully marine environment to terrestrial conditions, which occurred here during the Silurian Period. The onset of red bed conditions brought about by the closure of the ocean probably occurred at the end of the Llandovery or during the Wenlock times. This can be compared with the Welsh Borderlands where the Old Red Sandstone facies deposition is of Downtonian age. Here at Ree Burn and Glenbuck Loch the lowest beds of the sequence (the marine Smithy Burn Siltstones) are possibly of Upper Llandovery age, with the overlying greywacke Ree Burn Formation possibly being later Llandovery or Wenlock in age. Above these lies the Parisholm Conglomerate which is an alluvial fan deposit with derived, presumed Wenlock, stromatoporoids and bryozoans in its angular pebbles. The remainder of the pre-Old Red Sandstone succession comprises the Glenbuck Group, the Hareshaw Conglomerate and the Quarry Arenite, all of which are probably of Wenlock/Ludlow age. The Ree Burn Formation is famous for yielding very early phyllocarid crustaceans of the genus Ceratiocaris (fossil shrimp), whilst early examples of vertebrates have also been collected from the site.