Byne Hill

Also within

Ayrshire and Arran County

Condition (NatureScot)

Geology & landscape

Geological Period: Ordovician · Rock Type: Gabbro, Serpentinite

Landscape processes: Volcanic / Igneous

Description

BYNE HILL The site is located approximately 3km south of Girvan and comprises the summit and south-eastern slopes of Byne Hill. Byne Hill is one of four SSSIs forming the Ballantrae Complex, which is of Ordovician age (approximately 480 million years ago) and consists of three belts of pillow lavas and associated sediments, separated from each other by ultramafic intrusive rocks. The Complex shows many of the features of an obducted ophiolite although geochemical studies indicate that the various igenous rocks were generated in a variety of tectonic settings and have since been tectonically juxtaposed. At Byne Hill serpentinites of the northern serpentinite belt of the Ballantrae Complex are intruded by a large plutonic complex. The steep south-east facing slope of the hill exposes a variety of rock-types ranging from gabbro at the lower levels through diorite to trondjhemite higher on the hill. The diorites are thought to be hybrid rocks formed by reaction between a trondjhemite melt and the crystalline gabbro into which it was emplaced. Alternatively they may be related through fractional crystallisation. The rocks of the Byne Hill intrusion are comparable to those developed in magma chambers within oceanic crust. The Ballantrae Complex provides one of a few rare examples of ocean crust from the floor of the Iapetus Ocean and thus plays a crucial part in the reconstruction of Scottish geological history. Byne Hill provides a piece of vital evidence in the interpretation of the complex.