Natural England - Geology glossary (S to T)
Geology glossary (S to T)
This page of the glossary covers S to T. You can navigate to the next section from the links at the bottom of this page.
| Sandstone A rock typically composed of sand grains that range in diameter from 1/16 millimetre to 2 millimetres. |
| Sarsen A cemented sandstone boulder of Tertiary age typically found in southern England. Also refers to standing stones made of this material, as at Stonehenge and Avebury. Known as "greyweathers" when found in situ. |
| Schist Metamorphic rock dominated by parallel oriented fibrous or platy minerals such as mica, formed by compression of siltstone or mudstone. |
| Sedimentaryenvironment The environment in which sediment accumulates. |
| Sedimentary rock A rock made from the consolidation of solid fragments, as of other rocks or organic remains, or by precipitation of minerals from solution. |
| Serpentinite A low-grade metamorphic rock composed primarily of the mineral serpentine. Serpentinite is the alteration product of the igneous rock peridotite. |
| Shale A layered sedimentary rock composed of detrital sediment particles less than 0.004 millimetre (clay-size) in diameter which, in comparison with clay, is compressed and contains virtually no water. |
| Sill A sheet-like body of igneous rock which cuts across the bedding or structural planes of the host (older) rock. |
| Silurian A Period of geological time, dating from about 443 to 417 million years ago. |
| Slate A fine-grained, foliated metamorphic rock that develops from clay rich sediments and tends to split into thin, flat sheets. |
| Strata Layers of sedimentary rocks (singular stratum). |
| Stratigraphy The branch of geology that studies the arrangement and succession of strata. |
| Structural geology The scientific study of the geological processes that deform the Earth's crust and create mountains. |
| Subduction The sinking of oceanic crust beneath continental crust at a plate boundary. |
| Subsidence The lowering of the Earth's surface, caused by such factors as compaction, large scale faulting, a decrease in groundwater, mining or the pumping of oil. |
| Syncline A concave fold, the central part of which contains the youngest rocks. |
| Talus A pile of rock fragments lying at the bottom of the cliff or steep slope from which they have been derived. Also know as scree. |
| Tertiary A Period of geological time, dating from about 65 to 1.8 million years ago (comprising both Palaeogene and Neogene periods). |
| Till See boulder clay. |
| Topography The set of physical features, such as mountains, valleys, and the shapes of landforms, that characterises a given landscape. |
| Triassic A Period of geological time, dating from about 248 to 205 million years ago. |
| Trilobite Trilobites were early invertebrates with a segmented body and an exoskeleton. They belong to the same group as modern-day crabs, insects and spiders. Trilobites were a dominant component of marine faunas during the early Palaeozoic. |
| Tundra A zone between the perpetual snow and ice of Arctic regions and the tree line. Tundra has permanently frozen sub-soil supporting low-growing vegetation such as lichens, mosses, dwarf shrubs and stunted trees. Tundra comes from the Finnish word tunturia, meaning treeless plain |
| Tuff A volcanic rock made up of consolidated ash. |
| Turbidity Current A rapidly moving sediment–laden body of water sometimes caused by earthquakes and slumping. The sedimentary deposits that form as the current loses energy are called turbidites. |
