Glossary
S
| Term name | Description |
|---|---|
| Special Area of Conservation (SAC) | A designation under the Habitats and Species Directive protecting particular habitats and/or species |
| Salmonid | A fish species belonging to the salmon and trout genus Salmo |
| Schist | A fine–grained metamorphic rock, rich in mica. Formed by heat and pressure on a sedimentary sandstone, often during mountain–building periods |
| Scree | An alternative term for talus, broken rock material that has fallen off a cliff face and gathered at the base of the slope, accumulating into considerable 'fans' of unstable rock material |
| Seasonality | way in which natural processes that change over the seasons |
| Section 50 Agreement | A legal agreement between a local authority and a landowner, binding the latter to certain actions, under Section 50 of the planning acts |
| Semi-natural | Not completely natural; of vegetation, that which would normally occur naturally but which has been altered in some way - cleared, reseeded/planted - in the pas |
| Sheep rubs | This is usually a scar or un-vegetated area of land which is caused by the action of animals. |
| Shieling | describes a temporary, summer, grazing place in the hills, often with simple remains of stone–built huts for people to live in |
| Shingle | A bank or bed of coarse, water–worn gravel on river banks and beaches |
| Solifluction | The process of mass movement caused by a mobile soil layer moving across a frozen surface; occurs in spring when top layer melts and is lubricated, thus moving by gravity downslope |
| Special Protection Area (SPA) | An area designated by the species Directive to protect particular bird species and their habitats |
| Species | A group of organisms formally recognised as distinct from other groups; the basic unit of biological classification |
| Stadial | The stage in a period of glaciation when ice advances and temperature drops. Also known as a glacial |
| Stagnation | The period when an ice sheet or part of a glacier – dead ice – is melting in situ because the climatic conditions cause the ice to melt more quickly than it is being produced |
| Stakeholders | A generic term used for any individual or group that might have an interest and/or role in an issue or decision and/or its solution |
| Stillstand | The period when the melting of a glacier matches the speed with which ice is being produced and transported by the glacier. The glacier front remains more or less stationary, at the same point in the valley, leading to the formation of an end moraine |
| Sub-arctic | A zone of the Earth where temperatures are not quite as cold as within the Antarctic/Arctic circles |
| Subduction zone | The zone below oceanic trenches; the oceanic crust is thrust downwards by a more mobile crustal plate affected by seafloor spreading and collides with another oceanic or continental plate. As it descends, the sediments are scraped off and deformed, and the oceanic crustal material is melted and resorbed between 100 and 300 km depth |
| Sublimation | The melting and evaporation of snow into water vapour, without passing through a liquid phase |
| Substrate | The underlying layer of a stream or water body on which plants grow and animals rest |
| Sustainable development | Development that meets the needs of the present generation while maintaining the ability to meet the needs of future generations |
| Sustainable management | Management that takes into account the environmental, economic and social consequences of its practices in terms of |
| Saproxylic | A species dependant at some stage in its life cycle on dead wood, such as fallen trees or branches. |
| Sedimentary | Of rocks, formed from dead organisms and eroded rocks which settle usually under water and form a sediment. Examples are limestone and chalk. |
| Striations | A long scratch biting into a rock surface. Most glacial striations are a result of abrasion by the fragments incorporated in the ice. These striations are only a few millimetres across. |
