fracture in limestone and other sedimentary rocks. Stylolites result from compaction and pressure solution during diagenesis.Surficial - Of or pertaining to the surface.Syenite - A coarse grained igneous rock of intermediate composition, composed essentially of alkali-feldspar to the extent of at least two thirds of the total, with a variable content of mafic materials, of which common hornblende is characteristic.Syncline - Geological fold with strata dipping inwards towards fold axisSyntaxis -T[edit]Table Mountain Group - a group of rock formations within the Cape Supergroup sequence of rocks.Talus - Scree is a collection of broken rock fragments at the base of crags, mountain cliffs, volcanoes or valley shoulders that has accumulated through periodic rockfall from adjacent cliff faces. Landforms associated with these materials are often called talus deposits.Tectonics - large-scale processes affecting the structure of the earth's crust.Tephra - Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size or emplacement mechanism. Once clasts have fallen to the ground they remain as tephra unless hot enough to fuse together into pyroclastic rock or tuff.Tethys Ocean - (Greek: ) - ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.Till - Till or glacial till is unsorted glacial sediment. Glacial drift is a general term for the coarsely graded and extremely heterogeneous sediments of glacial origin. Glacial till is that part of glacial drift which was deposited directly by the glacier.Tillite - Till which has been indurated or lithified by subsequent burial into solid rock, is known as the sedimentary rock tilliteTopography - the arrangement of the natural and artificial physical features of an area.Tor - a large, free-standing residual mass (rock outcrop) that rises abruptly from the surrounding smooth and gentle slopes of a rounded hill summit or ridge crest.Trachyte - A fine grained igneous rock type of intermediate composition, in most cases with little or no quartz, consisting largely of alkali-feldspars (sanidene or oligooclase) together with a small amount of coloured silicates such as diopside, horneblende, or mica.Travertine - a terrestrial sedimentary rock, formed by the precipitation of carbonate minerals from solution in ground and surface waters, and/or geothermally heated hot-springs.Triclinic - In the triclinic system, the crystal is described by vectors of unequal length, and none of the three vectors are orthogonal to another.Tuff - A rock formed of compacted volcanic fragments, some of which can be distinguished by the naked eye. If the fragments are larger than the rock grades into an agglomerate.Tundra - a vast, flat, treeless Arctic region of Europe, Asia, and North America in which the subsoil is permanently frozen.Turbidite - the deposit of a turbidity current.Turbidity current - a current of rapidly moving, sediment-laden water moving down a slope through water, or another fluid. The current moves because it has a higher density than the fluid through which it flows.U[edit]Ultramafic - Almost feldspar free. Ultrabasic. [dunite, peridotite, pyroxenite]Urchin - or sea urchin - small, spiny, globular animal belonging to the class of Echinoidea. Urchins inhabit all oceans. Their shell, or "test", is