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Western Mournes Complex - OverviewDown
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Summary Full report
Site Type: Inland exposure
Site Status:
District:
Grid Reference: J234273, J178181, J184250, J165225, J155200, J129222, J145192
Rocks
Rock Age: Quaternary (Late Midlandian)
Interest
Other interest: No data, No Data, drumlin, recessional moraine

Summary of site:

The superficial deposits lying on top of the granites of the three major valleys of the western Mournes (the Kilbroney, Glen and upper Shanky’s complex; the Ghann and the Moygannon), and those of the lowland area from Rostrevor to Burren about 7km to the north west, tell a story starting about 15,000 years ago and ending with the final melting of the glacial ice.

In the closing stages of the last major glaciation, called the Midlandian, ice had again advanced south into the Carlingford Lough area following a melt-back in the middle of the period. The valley glaciers, on reaching the lowlands at Rostrevor and immediately north of Warrenpoint, were no longer confined and spread rapidly and widely into the lowlands. This movement of thin ice over boulder clay, perhaps accelerated by the proximity of the sea, sculpted the saturated deposits into drumlins. The north-west/south-east orientation of the long axes of the drumlins reflects the direction of ice flow down the Carlingford valley, the flooded area now Carlingford Lough. With the general warming towards the close of the Midlandian the glaciers began to melt. Drumlins in the lowlands were the first to be exposed, initially with patches of stagnant ice trapped in the muds and gravels between them. Then the retreat of the glaciers into the upland valleys began. For periods the ice flow matched the rate of melting so the glacier snouts appeared to stand still while shedding their loads of glacial rubbish. These linear mounds of clays, sands and gravels, matching the form of the glacier snouts, are moraines; a whole train of them marks the retreat of glaciers up the valleys towards the Spelga Pass. Bedrock is not seen in these valley bottoms and the total thickness of the deposits is unknown. These moraines match the pattern seen elsewhere in the area, particularly in the valleys of the central Mournes. While adding to our understanding of the dying stages of the last glaciers in the Mourne Mountains, this parch of lowland and the valley deposit are less clear-cut than those of the Central Mournes and are, therefore, not proposed for designation.


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