Holocene

The Holocene is the current interglacial. Commencing at 10, 000 BP (Before Present), temperatures rose abruptly and have remained close to those of the present. By around 7,500 BP the climate in parts of Scotland was as warm as today. Thereafter temperatures tended to decline, but the several warm phases lasting several centuries seems to have occurred between 3,100.-2,800, during the Roman period and again from 1,100-700 BP. After 1300 AD, the climate cooled as the Little Ice Age began, with the coldest years around 1700. The trend since 1850 has been towards warming, with recent years seeing some of the highest average temperatures of the last few centuries.

The rapid increase in temperatures at the start of the Holocene allowed colonisation of well-drained ground by birch, hazel and pine. On the broad valley floors basin peat began to accumulate. Sea level remained below its present level between 9500 and 7000 years ago but then rose to ~8 m above OD for the next 2000 years. Along the coast erosion by the sea stripped away glacial deposits to reveal cliffs and lower pre-existing shore platforms. These platforms are covered with raised beach deposits comprising gravel, sand and littoral shells. Terraces of silt and sand along the River Tyne are remnants of contemporaneous estuarine or carse deposits.

During the last 5500 years the sea has gradually fallen to its present level. Erosion of glacial and postglacial deposits has continued to feed fresh sediment into dynamic coastal systems. On shore platforms change has been limited, with localised lowering and erosion. On sandy and muddy shores the changes have been much more pronounced. Beach configurations have changed markedly as sand has been transported by longshore drift into Tyne Mouth and Aberlady Bay. Salt marshes have built up in sheltered locations. Substantial volumes of blown sand have accumulated on the postglacial raised beaches as dunes. Locally, as at Gullane, even the cliff faces of the main postglacial raised shoreline are covered by sand.

Away from the coast recent erosion and deposition have been confined to river valleys. In the Lammermuir Hills the main drainage system is the Whiteadder Water and its tributaries. Where cut in rock these rivers form narrow valleys with little alluvium but these valleys also show long open reaches. Here the river patterns switch from meandering at low water to braided during floods, a reflection of the high bed load on these floodplain. Below East Linton, the River Tyne along the John Muir Way has laid down extensive alluvial terraces, the higher and older terraces consisting of sand and gravel, the lower of silt and clay, all graded downstream to beach deposits. The Tyne and other smaller rivers have a history of severe flooding. Extreme examples of erosion in loose conglomerates has formed slit gorges, as in Sheeppath Dean, and produced the sculptured badlands topography of the Lammermuir Deans.

The Holocene has seen the sequential development of the vegetation, with the influence of man becoming progressively greater after 4000 years ago.