The Area of the Map

This map shows an area of about 4.2 km by 2.2 km centred on the small lake of Driminidy Lough. This lake and surrounding bog is probably of early post glacial origin, but this has yet to be confirmed. This will be done by ascertaining the full depth of the sediment and obtaining radiocarbon dates for some samples of organic matter, most crucially from the bottom of the deposit. A core will be taken, either from the bog or from the lake bed sediment, and this will be sampled, processed and analysed.

Of particular interest is the outlet from the bog / lake depression that leaves from the south west corner and flows down along the course of the bog road until it meets the other outlet, which it joins and they both flow into the Dromduvane stream. This drainage channel is now dry, being at a slightly higher level - 1 m or less - than the active drainage channel in the NW corner. The townland boundary between Kilscohanagh in the north and Driminidy North to the south follows this dry drainage channel, including that part of the first drainage channel after this one joins it. The Dromduvane stream is also followed by various townland boundaries.

That the townland boundary - townlands are supposed generally to have been created in antiquity - should follow this southern channel suggests that this channel may have been the active and flowing channel at that time. The current drainage channel was therefore possibly created later. We can conjecture why this would have been done - possibly when the road was established and a causeway constructed across the original channel. This may have blocked the channel, making the lake level rise until the current channel started to flow, and this then eroded down until it reached its current level below the original channel.

The bog road appears to be a relatively recent addition to the landscape - it does not appear on the 1st edition OS 6 inch map of about 1840, but it does on the 25 inch OS map of about 1880 (this can be checked on the OSI website here). Possibly this road across the low lying poorly drained land was built as part of a famine relief scheme. No townland boundaries follow this road - except where the bog road follows stream courses. This does raise the interesting possibility that townland boundaries - supposedly of great antiquity, but in reality we do not know for sure - may be indicators of the antiquity of the features they follow. It is noticeable that the road from Bredagh Cross north over the hills to Drimoleague - prior to the bog road the main route between the two - is followed all along its route by townland boundaries.

Other points of interest -

• The lake lies in a band designated as flat alluvial glaciofluvial plain - this refers to the action of meltwater coming from the ice. It may carry a heavy load of sediment and so can be very abrasive, and also potentially deposits a lot of sediment. In addition the flow can fluctuate enormously as melting and freezing cycles change. Thus the smoothing and levelling effect of such systems can be extreme, eroding protruding features of the landscape and filling hollows with sediment. We must imagine this happening in a landscape with ice present to at least some degree, and probably a complete absence of plant life. The land surface will have been very unstable and easily moved around.
• The same band of land is also marked as a deglaciation landform, as a glaciofluvial terrace. The action of glacial meltwater carrying substantial amounts of sediment continued as the ice melted at the end of the ice age. It would be hard to determine when the lake was formed or the glacial sediments deposited since the only practical opportunity for dating will be radiocarbon dating organic sediments - and these obviously would not have been deposited until the climate had improved and land surface became more amenable to organisms. Possibly the first organisms to get established would be diatoms and other microorganisms such as algae in the lakes and stream. These may be found in sediments below any organic sediment such as peat, and will be one of the focal points of the ongoing investigation.