Glandart Lake
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Three dimensional rotatable and zoomable models (topo-models) of Glandart Lake have been constructed to illustrate the difference between the surveying strategy on the digital surface , or terrain, models that result. These can be found
on this page for the elevation model based on a 25 m survey grid(opens in a new tab),
and on this page for the elevation model based on a 25 cm survey grid(opens in a new tab).
Glandart Lough lies at the top of a west facing slope of the lower southern part of Mullaghmesha (Mullach Méise - O'Donovan translated as 'top of the dish', but it may be an obsolete term for 'top of the altar'), a mountain in West Cork reaching 490 m, and about 2.6 km west of Castledonovan. This lake in fact is unnamed on all the Ordnance Survey maps from the first edition of c 1840 right through to the modern edition or the Irish Ordnance Survey Discovery series maps. However, the name Glandart Lough has been applied for convenience since it lies within Glandart (Gleann Dairte) townland, translated by John O'Donovan in 1841 as the 'Glen of the Heifer'.
Local enquiry has yet to be made to ascertain the local knowledge of this lake. To date no information has been obtained. A local lady who reputedly knew a lot about the area and retained memories from long ago, sadly passed away just a few months before this project started. Her knowledge was lost with her.
It is worth noting that Chief O'Neill, the celebrated collector of Irish traditional tunes, who became Chicago's Chief of Police, hailed from Trawlebane, to the west. One of the tunes, a jig, that he collected and included in his published collection was named – possibly by him - 'East to Glandart'. It is known that many of the tunes he collected, having no names, he named using placenames familiar to him from this area.
Glandart Lough lies at a height of between 330 m and 340 m above sea level, with a total surface area of about 0.4 hectares, and a circumference of 230 metres. It is largely circular.
It lies at the top of a steep slope, with only a very small amount of land to the east at a higher level. Surrounding high ground to the north and south are separated from the lake by valleys that extend deeper than the lake level and that drain to the west. The water of the lake is restrained from flowing down the slope to the west by a narrow bund that extends just 1.5 to 2 m above the lake level and is only some 8 to 10 m wide. Glandart Lake is thus perched right on the edge.
Glandart Lough lies within a band of the Castlehaven Formation which, with the older Gun Point formation outcropping further to the east north east, lies within the core of an anticline, flanked by the younger Toe Head, and then the Old Head, Formations. These are all essentially a very similar series of sedimentary rocks, principally sandstone, siltstone and mudstone. These are generally not massive sedimentary deposits, but very heavily foliated and relatively easily shattered and split. Although the siliceous sediments, with a hard siliceous cement, can create an impermeable surface, the degree of faulting and foliation means that the bedrock is very often free draining.
The next geological period to affect West Cork, and more specifically the area around Glandart Lake, is the ice ages. This is a series of warm and cold climatic fluctuations that affected the whole of the Northern Hemisphere over the last 2 million years
There are two places on the water's edge, one to the northern side, one to the southern, both eventually leading across reasonably flat ground to valleys that drain away west. At these places the ground is boggy and clearly any rise in water level of the lake will result in overflow, by seepage, in these two places.
The lake is probably a kettle hole, that is, a depression formed by a buried ice block within diamict (boulder clay) deposit at the end of the ice age, which then melts, and all sediments overlying the ice block collapse into the depression.
The lakebed sediment has yet to be sampled - access is not simple.