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In terms of time scale in geology, Quaternary is the present-day time and it began 2.6 million years ago. A lot of this time period relates to the Ice Age.
Quaternary geomorphology is the record of landscape features that were created in the last 2.6 million years. In Ireland, movement of glaciers and ice sheets created many of these features. The main features included are; erratic dispersion; landforms created under ice; landforms created at the ice margin and landforms created by mountain ice.
An erratic is a rock which has been moved by ice and deposited in another location. Erratics are identified as the erractic rock type is different to the usual rocks found in that location. Geologists study the composition of erratics and can determine where the rock came from (the source). Once the source is known, the direction of ice flow can be determined (Inferred Erratic Path). The end of these erratic flow paths are termed erratic limits.
Subglacial landforms are created beneath the ice. They were created during ice expansion. An example of these are drumlins. Drumlins are smooth, oval-shaped hills, shaped like a half-buried egg. They are made up of glacial till. As the glaciers retreated, they left these deposits behind. The exact process of drumlin formation is unknown. Mega-scale glacial lineations, like drumlins, are typically smooth hills of subglacially-deposited material, but are much longer. They are produced beneath zones of fast-flowing ice. Striae (Glacial striations) are scratches or gashes cut into bedrock by glacial movement, usually by particles embedded in glacier ice. They provide a reliable record of ice flow direction.
Deglacial landforms are created at the ice margin. They were created during ice retreat. A moraine is material left behind by a moving glacier. Kame terraces, deltas and fans are all ice marginal landforms deposited by water issuing from a glacier.
Landforms created by mountain ice include corries and trimlines. A corrie (cirque) is a half open, steep-sided round hollow made in the side of a mountain by the action of a glacier. A trimline is a clear line on the side of a valley formed by a glacier. The line marks the most recent highest extent of the glacier. The line may be visible due to changes in color to the rock or to changes in vegetation on either side of the line.
Geologists map and record evidence during field visits, from air photographs and from Digital Elevation Models (DEMs). This data along with boreholes (a deep narrow round hole drilled in the ground) and geophysics help to create the map. Areas are drawn on a map to show where features are found, lines are drawn to show the direction of other features and some features are shown as points.
We collect new data to update our map and also use data from other sources.
This map shows the currently mapped glacial landforms in Ireland.
This map is to the scale 1:50,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 500m.
It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas).
Features include: erratic carriages (sources and sinks), subglacial landforms (lineations, striae and moraines), ice-marginal landforms (meltwater and deglacial and mountain glaciation (corries and trimlines).