Glossary of Terms

Aquifer
Is described as a permeable geological stratum or formation that can both store and transmit water in significant quantities.

Bedrock
Bedrock is the native consolidated rock underlying the Earth’s surface

Benchmark
A benchmark is a is a point of reference for a measurement. In surveying a bench mark is specifically any permanent marker placed by a surveyor with a precisely known vertical elevation. These markers are then used as starting (control) points by subsequent surveyors and other users to establish the elevation of nearby points.

Buffer
A zone of user specified distance around a point, line or area.

CAD
Computer Aided Design. Software programs for the design, drafting and presentation of graphics. Originally designed for manufacturing drawing, now widely used in mapping.

Cartesian co-ordinates
With Cartesian co-ordinates a position is defined in 3 dimensional space by an X, Y, Z co-ordinate triplet. The Z axis passes through the centre of the earth (or reference ellipsoid) and the poles, the X axis through the centre and the Greenwich meridian, and the Y axis at right angles to these. These days

Collieries
A coal mine and it’s accompanying structures are known as colleries.

Contour
A line drawn on a map joining locations of equal height. Many of these at different heights indicate the shape of the landscape. This is a type of isoline.

Control
A system of points which are used as fixed references for positioning other surveyed features. Check this

Dataset
A data file or collection of interrelated data.

Datum
Is a known reference point on the earth's surface against which position measurements are made

DEM
Digital Elevation Model.

DSM
Digital Surface Model

DTM
Digital Terrain Model is a 3D representation of the Earth's surface. It's construction includes a height model (i.e. a DEM) and overlaid with map data relating to features on the surface (i.e. Map Data or Aerial Photograph).

Dyke
In geology refers to an intrusive igneous body.

Easting
First measurement of a grid reference used to specify the location of a point on a rectangular co-ordinate system. The distance measures eastward from the origin of a rectangular co-ordinate system.

Ellipsoid
A surface, all of whose cross sections are circular (includes the sphere)

Estuarine
Means relating to, formed in, or found in an estuary

Eutrophication
Physical, chemical and biological changes in a water body as a result of the input on nitrogen and phosphorous.

EPA
Environmental Protection Agency has responsibility for a wide range of licensing, enforcement, monitoring and assessment activities associated with environmental assessment it is responsible also for regulating activities that have significant polluting potential.

False Origin
Location of the starting co-ordinates picked to the south and west of the true origin of a rectangular co-ordinate system. False origins are used to avoid negative co-ordinates

Faults
Faults are planar rock features which show evidence of relative movement

Geo Directory
Spatial database containing address and location information for every building in the Republic of Ireland. Developed in conjunction with An Post

Geodesy

Geoid
The geoid is defined as a surface on which the earth's attractive (i.e. gravitational) forces are everywhere equal, i.e. a gravimetric equipotential surface. The geoid is of fundamental importance in determining positions on the earth's surface as most measurements are made with reference to this surface.

Geopoint
Means the specific mapping co-ordinate that corresponds as nearly as possible to the location specified by you on the interactive map viewer when ordering an environmental report.

GIS
Geographical Information System is a technology that is used to view and analyse data from a geographical perspective. A Geographic Information System is a system of hardware and software used for the storage, retrieval, mapping and analysis of geographic data.

GSI
Geological Survey of Ireland is the National Earth Sciences Agency. It is responsible for providing geological advice and information and for the acquisition of data for this purpose.

Hydrogeologogy
Is a branch of earth Sciences dealing with the distribution and movement of groundwater in the soil and rocks of the Earth’s crust.

ING
Irish National Grid Co-ordinate reference system which is now commonly used. When using this projection positions on maps are expressed in two dimensions as Eastings (E) and Northings (N) relative to a false origin. Re-projection of two dimensional grid co-ordinates (E,N) back into geographic or ellipsoidal co-ordinates (F, ?) are possible by using standard formulae.

ITM
Irish Transverse Mercator is a GPS compatible mapping system that takes advantage of the accuracy of GPS whilst minimising mapping distortions

Karst
Is a term used worldwide to describe the distinctive landforms which develop on rock types that are readily dissolved by water. E.g. Springs, turloughs, caves, swallow holes and enclosed depressions.

LiDAR
Light Detecting and Ranging. LiDAR is a remote sensing technology that uses laser scanning to collect height or elevation data. These points are the objects the laser hits after it is emitted from the scanner. After capturing the raw point cloud each point can be classified into different layers e.g. Ground, Buildings and vegetation. The final output from the point cloud is either a Digital Terrain Model (DTM) or a digital surface Model (DSM).

Lime Kiln
Lime Kilns date from the 18th century and were still in use unitl the 1940’s in some areas. By lighting fires in these kilns and adding crushed limestone, lime was produced for use as fertilizer in the fields and also for whitewashing cottages.

Vector
to be provided..

Foundry
The buildings and iron works for casting metals

Marsh
A type of wetland

Northing
The second measurement of a grid reference used to specify the location of a point on a rectangular co-ordinate system. The distance measured northward from the origin of a rectangular co-ordinate system.

Photogrammetry
The science of using aerial photography and other remote sensing imagery to obtain measurement of natural and man-made features on the earth

Pictometry
to be provided...

Polygon
Polygons are representations of areas. A polygon is defined as a closed line or perimeter which completely encloses a contigous space and is made up of one or more links.

Raster
Raster data provides a map image formed by a matrix of pixels arranged in rows columns, which can be displayed on a computer screen.

Sluice
A water channel that is controlled at it’s head by a gate. A sluice gate is traditionally a wooden or metal plate which slides in grooves in the side of the channel.

Turlough
A turlough is a unique type of disappearing lake found only in limestone areas of Ireland, most commonly found west of the Shannon. Most turloughs flood in Autumn then usually dry up in Summer.

Vulnerability
Is a term used to reperesent the intrinsic geological and hydrogeological characteristics that determine the ease with which ground water activities may be contaminated by human activities

Weir
Is a small overflow type dam commonly used to raise the level of a small river or stream

X Y Co-ordinates
These are references on the National Grid and ITM Grid (GPS compatible) that identify a particular place on the earth. The X co-ordinate identifies the exact Easterly location while the Y co-ordinate identifies the exact Northerly location. The intersection of these two co-ordinates pinpoint the relevant object or location concerned.