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Louth and Meath Coastline
Lú agus na Mí Chósta

Overview

Louth and Meath are located on the east coast of Ireland, north of Dublin.

Louth is Ireland's smallest county but its coastline stretches over 90km from Carlingford Lough in the north to the Boyne Estuary in the south.

Although, Meath is a much larger county it only has approximately 12km of coastline stretching south of the Boyne estuary to Gormanston.

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INFOMAR Survey History

Survey coverage has been achieved over a large area of the seabed off the Louth & Meath coast. The RV Celtic Voyager mapped the offshore areas. Dundalk Bay and the shallower areas were mapped by the RV Keary, Cosantóir Bradán & RV Geo. The Boyne Estuary and coastline was surveyed by RV Keary, RV Tonn & RV Geo in October 2015.

Read more about some of the survey legs on our Blog by clicking on the links below.

INIS-Hydro Completion

INIS-Hydro - 2012 Progress

INIS-Hydro Project

CV10_01 Irish Sea Priority Area

CV09_05 Survey off North Dublin coast

Coverage from the survey legs of Louth & Meath coast (Click on image for more detailed map).

 

Survey Coverage polygons can be downloaded as a shapefile from our Interactive Web Data Delivery System (IWDDS).

Select your area of interest. Vector datasets - Offshore - Offshore Shapefiles

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Bathymetry (Water Depth)

Water depth varies from 4 to -74m.

A detailed .pdf chart of the bathymetry of Louth & Meath can be downloaded by clicking here.

You can download Bathymetry xyz data from IWDDS

(Data Type: Vector Datasets, Region: Offshore, Theme: Bathymetry (Survey Leg) entire survey leg or Bathymetry (Survey Line) for individual tracklines. Take note of the survey names in INFOMAR Survey History.

You can also download the bathymetry data in ArcGIS GRID format

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Shaded Relief

The 3D appearance is achieved using software called Fledermaus. By using some vertical exaggeration, artificial sun-shading (usually as if there is a light source in the nw 315°) and colouring the depths using various colour maps, it is possible to highlight the subtle relief of the seabed. This helps us to quickly understand the variation in depths.

Shaded relief bathymetry image of the Louth & Meath coast. (Click on image for more detailed map)

Detailed MBES shaded relief image of Dundalk Bay reveals a large channel feature in the centre of the bay. It's relatively wide to the west and then becoming distinctly narrow in a seaward direction. The origin of this is unknown – perhaps it is an ancient river channel, dating from when sea-levels were lower, but is now part of the marine landscape? (Click on image for more detailed map)

All of our Charts for Louth & Meath can be downloaded in pdf format from this page.

Download Shaded Relief Bathymetry Geotiffs from our Interactive Web Data Delivery System (IWDDS)

Select your area of interest. Offshore Geotiffs - Bathymetry Shaded Relief Geotiffs.

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Backscatter

Multibeam Systems also collect additional information, including the strength of the acoustic signal (or return) from the seafloor. This is known as Backscatter. Differing seafloor types, such as mud, sand, gravel and rock will have different Backscatter values depending on the amount of energy they return to the sonar head. Rocky areas will typically have high returns while soft sediments like mud are more likely to absorb energy and have low Backscatter returns. These differing values are used to generate a grey-order image (i.e. dark for high returns, bright for low returns) of the seabed which can be used to examine the nature of the seafloor.

Overview backscatter image of the seabed surveyed off the Louth & Meath coast. (Click on image for more detailed map)

Detailed .pdf backscatter charts can be downloaded by clicking here

Download Backscatter Geotiffs from our Interactive Web Data Delivery System (IWDDS)

Select your area of interest. Offshore Geotiffs - Backscatter Geotiffs.

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Ground Truthing/Seabed Sampling

To verify the results of sonar data, it is important to collect physical sediment samples from the seabed. These may be from the surface where grabs are used or may penetrate through the seabed and retain the vertical structure of the sediment by using various coring methods. These samples are also critical for the confirming seabed classifications.

Several seabed sampling surveys were undertaken in the area as seen in the map below. Some of the area has had its seabed classified.

 

Sediment samples recovered from the seabed using a grab sampler. Sand and gravel, respectively.

Sample locations can be downloaded as a shapefile from our Interactive Web Data Delivery System (IWDDS).

On the IWDDS Select your area of interest. Vector datasets - Offshore - Offshore Shapefiles

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Seabed Classification

Seabed classification is an advanced process in which a backscatter image is interrogated using special software in order to divide it into areas which have similar characteristics. Areas which have a similar nature are grouped together and divided into separate classes. These classes are colour coded and developed into seabed classification charts.  

 The classification of the multibeam dataset from the East Coast resulted in the creation of a 5 class classification divided into Coarse sand and gravel (High biogenic content), Rock and Gravel, Gravel and Coarse Sand, Medium to Fine Sand and Mud to fine sand.

Seabed Classification Chart for the East Coast .(Click on image for more detailed map)

Further information about the classification process can be found in the Data Processing section.

For a more detailed .pdf chart of the seabed classification of the East Coast click here

You can download the Seabed Classification in ArcGIS GRID format data from IWDDS

(Data Type: ArcGIS GRIDS, Region: Offshore ArcGIS, Theme: Seabed Classification ArcGIS GRID

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Geology

Carlingford Lough Geology
Most of the coastline of Carlingford Lough is composed of sandstones and shales of the Silurian period. The bedrock on either side of the entrance, however, is predominantly limestone and shale. To the southwest of the lough are occurrences of an igneous rock called granite, which forms much of the Mourne mountains.

Dundalk Bay Geology
The southern and western coasts of Dundalk bay comprise sandstones and shales of the Silurian period. To the north, limestones and shales form the bedrock of the coastline, with the granites of the Mourne mountains rising up behind them. A feature of interest in the seabed data is a channel-like feature in the middle of the bay, relatively wide to the west and then becoming distinctly narrow in a seaward direction. The origin of this is unknown – perhaps it is an ancient river channel, dating from when sea-levels were lower, but is now part of the marine landscape?


Boyne Geology

The Boyne estuary, as it reaches the sea, passes through limestones and shales of the Carboniferous period. The area of limestone each side of the river is then bound to the north and south here by fault lines, beyond which lie sandstones and shales to the north, and slates, volcanics, shales and sandstones to the south. Note the headland of Clogherhead, which has the axis of a fold in the rocks passing through it – this structure may be the reason that the headland lies prominent towards the sea, while the land either side of it has been eroded westwards.

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Shipwrecks

Shipwrecks discovered in Louth & Meath.

Click here to download the Crusader shipwreck information sheet.

Click here to download the SS Topaz shipwreck information sheet.

Other information sheets can be downloaded using the link below.

To view the shipwrecks in Google please click here

Shipwreck locations can be downloaded as a shapefile from our Interactive Web Data Delivery System (IWDDS).

On the IWDDS Select your area of interest. Vector datasets - Offshore - Offshore Shapefiles

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INFOMAR in Google Maps/Earth

To view and navigate around the East Coast data in Google Maps/Earth, click here

To view and navigate around the shipwreck data in Google Maps/Earth, click here

 

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View data in the free iView4D

Download the free viewer here

Download the Louth & Meath Bathymetry 20m and shipwrecks here

Download the Louth & Meath Bathymetry 20m in colour here

Download the Louth & Meath shipwrecks in colour here

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Louth & Meath beneath the waves

Discover a new 3D view of Louth & Meath. What features lie on the seafloor? How were they discovered?

Click Here to view the Louth & Meath Story Map

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Data Access

Full details outlining the process to gain access to datasets for the bay above or all INFOMAR data can be found in the INFOMAR | Data page of this website.

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Return to Survey Details Map

Follow these links to your area of interest on the INFOMAR website:

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