Name

Ancient Shores

Date

2013

Stone Source and Type

Beach found metamorphosed Pre-cambrian Dalriadan sedimentary rock from the Moray firth

Description.

An informal shaped inkstone. The surface patterns suggest how the material eroded from the mountains of Laurentia once settled on an ancient shore before becoming again mountains but eventually to lie again on a beach.

Mineral Patterns.

Watered silk markings created by the different oxides in the sediments before metamorphosis.

Other info

Metamorphic Bedrock formed approximately 505 to 1000 million years ago in the Cambrian and Pre cambrian Periods. Originally sedimentary rocks formed in deep seas. Later altered by low-grade metamorphism. Dalradian sediments were all deeply buried, heated and compressed as a consequence of the Caledonian mountain-building event. Soft sediments were converted to sedimentary rock, then further deformed and metamorphosed so that we now find schists and marbles instead of the original sandstones, mudstones and limestones. As the rocks were squeezed between the converging crustal plates, the rock layers were folded and contorted, and often turned upside down. The resulting fold structures can be seen in many places along the Moray Firth coast. Before 542 million years ago, what part of the earth's surface would become Scotland was in the Southern Hemisphere, the Dalradian sediments were laid down in an expanding Iapetus Ocean on the margins of a continent we now call Laurentia; later in the Ordovician period these Dalradian sediments were deeply buried. compressed and heated.

Dimensions in centimetres

Length, 16.5  Width, 11.5  Depth, 2.6