A description of Lough Derg and its topography

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A description of Lough Derg and its topography


Lough Derg--Landscape--Topography--Description


“Lough Derg is a lonely sheet of water, extending from north to south, about six miles in length..."


Daniel O'Connor, 1843-1919


Daniel O’Connor, Lough Derg and Its Pilgrimages: With Map and Illustrations, pp. 23-4


J. Dollard, Dublin




Digitised by archive.org, sponsored by Harvard University


Public domain






Pilgrim handbook




54.616218, -7.876212



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“Lough Derg is a lonely sheet of water, extending from north to south, about six miles in length. Its greatest width from Portcreevy to the River Derg is fully four miles. It is thirteen miles in circuit, and covers an area of 2,140 statute acres. It is surrounded by a chain of mountains, some of which rise to a considerable elevation above the level of the lake. The Rev. Caesar Otway, in his Sketches in Donegal and other writers after him, from whom we should expect a more impartial description, if not so graphic, say that there is no grandeur in the scenery of Lough Derg, no variety in the outline, the mountains without elevation, neither tree nor green spot to relieve this sombre scenery. A more unfair or distorted picture the greatest enemy of the place could hardly give. Here, indeed, you have all the charms of Highland scenery, and much in addition. The extensive sheet of water, with rocky shores and numerous islands, is all that can be admired. In the background the mountains are of considerable and varying elevation.

And though heath is here the prevailing robe of nature, yet occasional patches of trees and bushes, with many a sunny slope and green sward and wooded island, relieve the scenery of its stem and wild aspect. But above and beyond all, the traditions and associations of the place impart to it an attraction and charm which no beauty of scenery could supply.

The lake is about 450 feet above the level of the sea ; while the highest surrounding mountains are Crockinnagoe, to the south-east of the lake, 1,194 feet ; Ardmore and Ougtadreen towards the north, 1,086 and 1,071 feet high respectively ; the mountains to the south and west not reaching an elevation of 1,000 feet.

The chain of hills towards the south of the lake forms the watershed between northern and southern Ulster, The streams flowing south of this chain of hills meet the Termon river at Pettigoe, thence flowing into Lough
Erne ; while the streams flowing northward empty into Lough Derg, and thence into the sea at Lough Foyle.

‘The basin of the lake is a huge quarry of the metamorphic rock, known as mike slate, or schist, upheaved in ages azoic by some fiery agent, so that the stratifaction is now almost perpendicular to the surface. It crops up all round the shore, and through the lake into numerous rocky islets and hidden reefs, whose projecting points are sharp as iron spikes, and render the navigation of the lake a matter of great caution.’*

* From an article in the Irish Monthly, January Number, 1878.”

Original Format



Daniel O'Connor, 1843-1919, “A description of Lough Derg and its topography,” Digital Derg: A Deep Map, accessed April 21, 2024, https://digitalderg.eu/items/show/27.