Description: Research ships working at sea map the seafloor. The ships collect bathymetry data. Bathymetry is the measurement of how deep the sea is. Bathymetry is the study of the shape and features of the seabed. The name comes from Greek words meaning "deep" and “measure". Backscatter is the measurement of how hard the seabed is.Bathymetry and backscatter data are collected on board boats working at sea. The boats use special equipment called a multibeam echosounder. A multibeam echosounder is a type of sonar that is used to map the seabed. Sound waves are emitted in a fan shape beneath the boat. The amount of time it takes for the sound waves to bounce off the bottom of the sea and return to a receiver is used to find out the water depth. The strength of the sound wave is used to find out how hard the bottom of the sea is. A strong sound wave indicates a hard surface (rocks, gravel), and a weak signal indicates a soft surface (silt, mud). The word backscatter comes from the fact that different bottom types “scatter” sound waves differently.Using the equipment also allows predictions as to the type of material present on the seabed e.g. rocks, pebbles, sand, mud. To confirm this, sediment samples are taken from the seabed. This process is called ground-truthing or sampling.Grab sampling is the most popular method of ground-truthing. There are three main types of grab used depending on the size of the vessel and the weather conditions; Day Grab, Shipek or Van Veen Grabs. The grabs take a sample of sediment from the surface layer of the seabed. The samples are then sent to a lab for analysis. Particle size analysis (PSA) has been carried out on samples collected since 2004. The results are used to cross-reference the seabed sediment classifications that are made from the bathymetry and backscatter datasets and are used to create seabed sediment maps (mud, sand, gravel, rock). Sediments have been classified based on percentage sand, mud and gravel (after Folk 1954).This dataset show locations that have completed samples from the seabed around Ireland. The bottom of the sea is known as the seabed or seafloor. These samples are known as grab samples. This is a dataset collected from 2001 to 2019.It is a vector dataset. Vector data portrays the world using points, lines and polygons (areas). The sample data is shown as points. Each point holds information on the surveyID, year, vessel name, sample id, instrument used, date, time, latitude, longitude, depth, report, recovery, percentage of mud, sand and gravel, description and folk classification.The dataset was mapped as part of the Irish National Seabed Survey (INSS) and INFOMAR (Integrated Mapping for the Sustainable Development of Ireland’s Marine Resource). Samples from related projects are also included: ADFish, DCU, FEAS, GATEWAYS, IMAGIN, IMES, INIS_HYRDO, JIBS, MESH, SCALLOP, SEAI and UCC.
Service Item Id: 27c9ef6e837a4ee3b08bc1dd7f870ead
Copyright Text: Geological Survey Ireland & Marine Institute