--- title: "Glossary of geography terms (N–Z)" chunk: 17/21 source: "https://en.wikipedia.org/wiki/Glossary_of_geography_terms_(N–Z)" category: "reference" tags: "science, encyclopedia" date_saved: "2026-05-05T08:06:30.234613+00:00" instance: "kb-cron" --- tidal creek Also tidal channel. A narrow inlet or estuary that is affected by the ebb and flow of tides from an adjacent ocean. Water in the lower portions of these channels tends to vary greatly in depth, salinity, electrical conductivity, and other hydrological properties over the course of the tidal cycle, but is often slow-moving and rich in organic sediment drained from upstream freshwater sources, making them important habitats for many species. tidal flat An extensive, nearly horizontal, and barren or sparsely vegetated tract of land at the edge of a sea or ocean that is alternately covered and uncovered by the tide. tidal prism The total volume of water that flows in and out of a coastal inlet or estuary with each cycle of the tides, excluding any freshwater discharges; i.e. the difference in the inlet's volume between the mean high and low tides. tidal range The difference in height between high tide and low tide at a given location. This range may vary over the course of the year, e.g. during neap tides and spring tides. tide The periodic rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the Earth's rotation. tide pool A shallow pool of seawater, supplied regularly by incoming tides, that forms on a rocky intertidal shore. tied island Also land-tied island. An island that is connected to a mainland only by a narrow spit or tombolo which may or may not be occasionally submerged. till See glacial till. timberline See tree line. time distance A measure of how far apart places are in terms of the amount of time it takes to travel between them (how long does it take to travel from place A to place B?). This may be contrasted with other distance metrics such as geographic distance (how far is it?) and cost-distance (how much will it cost to get there?). time geography Also time-space geography. An interdisciplinary perspective, ontological framework, and visual language in which space and time are used as basic dimensions of analysis of dynamic processes and events, including social and ecological interactions, environmental changes, and biographies of individuals. time zone A region of the globe that observes a uniform standard time for legal, commercial, and social purposes. Most time zones span about 15 degrees of longitude, and in each of these divisions the mean solar time at an arbitrarily selected meridian (usually one near the longitudinal center of the division) is made the standard time across the entire zone. Time zones tend to follow political boundaries between countries and their subdivisions, however, rather than strictly following the same meridian, because it is convenient for areas in frequent communication to keep the same time. Tissot's indicatrix Also Tissot's ellipse and ellipse of distortion. A mathematical contrivance used to illustrate the linear, angular, and areal distortions that result when projecting information from a curved three-dimensional geometric model such as a globe onto a two-dimensional map. A single indicatrix is traditionally a circle of determinate size drawn upon the surface of the globe, with center at specific coordinates; the extent to which this circle is deformed when the globe's coordinates are transformed onto a flat two-dimensional map makes apparent the nature of the distortion affecting nearby map features, such as the size and shape of landmasses, which might otherwise be difficult to visualize. Because distortion can vary greatly across a map, it is common for multiple indicatrices to be depicted at multiple points on the map, e.g. at major intersections of meridians and parallels. toe See snout. toeslope toll road Also tollway or turnpike. A public or private road or highway for which a fee or toll is charged to drivers for passage. tombolo A sandy or shingle-covered spit, bar, or isthmus connecting an island to the mainland or to another island (thereby forming a tied island). topocide topographic isolation The minimum great-circle distance between the summit of a mountain or hill and a point of equal elevation, representing a radius of dominance in which the summit is the highest point. topographic map Also relief map. A map that uses contour lines to represent the three-dimensional features of a landscape on a two-dimensional surface. topographic prominence Also autonomous height, relative height, or shoulder drop. A measure of the independence of a mountain or hill defined as the vertical distance between its summit and the lowest contour line completely encircling it but containing no higher summit within it; or, equivalently, the difference between the elevation of the summit and the elevation of the key col. Mountains with high prominence tend to be the highest points in their vicinity. topographical relief See terrain. topography The physical features of a place, or the study and depiction of physical features, both natural and man-made, including terrain relief. topological map A type of diagrammatic map which depicts the actual positional relationships between certain features but on which true scale is distorted and unnecessary detail is absent to accommodate other considerations (e.g. simplicity so as to aid understanding of a complex communications network or public transit system). topology In geographical studies, a discipline concerned with the mathematical analysis of enclosure, order, connectivity, contiguity, and relative position rather than with actual distance and orientation. Topological relationships are commonly expressed in terms of networks and depicted with topological maps. toponymy The study of placenames (known as toponyms), their origins, meanings, use, and typology. tor Also castle koppie or kopje. A prominent, free-standing rock outcrop that rises abruptly from the smooth slopes of a gently rounded hill or ridge. In the United Kingdom, the term is also used to refer to the hill itself. town A medium-sized human settlement that is generally larger than a village but smaller than a city, though the criteria for distinguishing a town vary considerably in different parts of the world.