As well as providing data online to the Irish public on the project’s website (www.infomar.ie), the INFOMAR team at Geological Survey Ireland also feed data to the European online portal EMODnet (European Marine Observation and Data Network).

This online viewer, which displays multiple datasets from across European seas (e.g. seabed minerals, substrates, bathymetry, geomorphology, etc.), is the result of gathering and harmonising data from a myriad of geological surveys and universities across Europe.

It is made possible by a network of organisations supported by the EU’s integrated maritime policy. While these seamless maps are available to the public for free online, they also assist the European Commission in terms of marine spatial planning. It is an example of the ‘collect once and use many times’ philosophy that is also followed by the INFOMAR project.

Submerged sites
A recent addition to the EMODnet portal is a work package called Submerged Landscapes. The importance of submerged archaeological sites has been growing steadily more apparent as human activity at sea has intensified – particularly with respect to marine construction projects that can disturb the seabed.

In order to assist with responsible marine planning, maps of now-drowned landscapes, where ancient humans such as those during the Palaeolithic and Mesolithic once lived, are required in order to identify potential archaeological hotspots. These are landscapes that were exposed during and following the peak of the last Ice Age, before rising sea levels inundated them and gave us the coastline we have today.

A strong example in the North Sea is the so-called ‘Doggerland’ — an ancient landscape hidden beneath the waves, once populated by prehistoric humans and now only visible through bathymetric and geophysical mapping.

The Irish seabed is no exception. While the extent of exposure of the shelf during and following the Ice Age is still being debated and requires further analysis, there is certainly evidence for potential submerged landscapes in both INFOMAR data and surveys carried out by various universities.

The question remains, however: How do we define a submerged landscape?

This recently required consensus among members of the EMODnet network and was agreed to during a series of international meetings. In short, a submerged landscape in this context is any seabed feature, be it on the seafloor or buried beneath, which can reasonably be deduced to have been a dry landscape feature during and following the peak of the last Ice Age (approx. 20,000 years ago).

Examples of such features are ancient river channels (known as palaeochannels), relict shoreline deposits, wave-cut platforms, ancient lake deposits and drowned forests and peats. Some of them are not visible even on the seafloor and must be detected through sub-bottom profiling with shallow seismic equipment (Figure 1), where the valley can be seen cutting through the layers below it.

Other palaeochannels are still present and visible in the seabed data, such as the incision in the bedrock that extends out from the mouth of Waterford Estuary (Figure 2) dating from when the coastline was further south during lower sea level.

There is an entire lost landscape hidden beneath the waves along the Irish coast. With further mapping by INFOMAR vessels and analysis of data collected, the team hopes to assist in piecing the country’s rich prehistory back together.

Eoin MacCraith GSI