Last Saturday morning dawned fine and fair and was just perfect for the two-stick dive by Sheephaven SAC to Dunloan Rock. Water temperature on-site was five degrees Celsius, with near perfect water clarity of over five metres at the maximum depth of 25 metres.
The divers used the morning as an opportunity to conduct the first dive of their Advanced Nitrox Course during which they calculated their Residual Minute Volume (RMV). Effectively this is the individual average breathing rate of a diver and from that figure a diver can predict how much air they will consume at different depths and for different dive times.
Dunloan Rock remains a haven of fish life, in contrast with other recently dived sites this winter and during this dive one Sheephaven diver observed a Lobster with a still wriggling fish in its claws, snatched from the school of Bib that persist in sharing in the same sheltered hole on the reef.
The bedrock formation of Mulroy Bay from Meevagh to Dunloan Rock on the western side starts with the Clonmass Limestone Formation which is made up of marble and schist, followed along the coast by the Sessiagh-Clonmass Formation which consists of a mixture of quartzite, marble and schist rocks. These formations give way eventually to Fanad Granite that dominates the northerly portion of the Rosgill Peninsula; this is a particular type of granite that contains Xenolithic Fancies. Such granite has quite distinctive pieces of other rock material imbedded in it and consequently produces a highly decorative rock for ornamental use. Granite is an igneous rock and this particular rock formation was laid down 440 million years ago in the Silurian- Devonian period.
Bedrock on the eastern side of Mulroy Bay at this location is also recorded as being Sessiagh- Clonmass Formation and on both sides of the bay the soil type is considered to be 80% Lithosols with 20% Rocky Outcrop and Peat and considered to be pasture land. The formation of Dunloan Rock itself appears to be foliated, that is a series of layers, which have become exposed and produces the ledges, crevices and holes that provide such excellent cover for the fish life observed on Saturday morning.