The light was established in 1831 by Robert Stevenson. The position is at latitude 58 degrees north, further north than Moscow. The light is flashing (4) White every 30 seconds. The tower is of white stone, 20m high. There are 51 steps and 9 ladder steps up to the top of the lighthouse tower.
Dunnet Head Lighthouse marks the most northerly point of the Scottish mainland – being some 2.35 miles North of John o Groats. Only 6.75 miles across the Pentland Firth lies the nearest point of the Orkney Islands. Erosion of the rock on which the original fog signal (built in 1899( stood, made it necessary to abandon it and to establish another fog signal nearer the lighthouse.
Most of Caithness is underlain by flatstones of the Middle Old Red Sandstone (ORS) that are mid Devonian in age, and were deposited as muds and sands in a large lake. the famous fossils fish beds of Caithness and Orkney occur in these rocks. Later in the Devonian period the lake was filled with sediment and the area dried out. Locally there was uplift and erosion before the Upper Old Red Sandstone was deposited. Dunnet Head and most of the Island of Hoy consist of red and yellow sandstone of the Upper ORS. These sandstones have sedimentary structures that indicate an alternation of deposition by rivers (fluvial) and sand dunes (aeolian) in a semi-arid environment. A few fish scales have been found on Dunnet Head, but they are rate.
The eastern margin of Dunnet Head is controlled by the Brough Fault. This N-S fault separates the Upper ORS from Middle ORS flagstones to the east. The rocks are highly deformed along the line of the fault. Later, probably in Permian times, a small volcanic vent punched its way through the sandstones, and is now seen in the Burn of Sinigoe.
copyright: Rachel Carson Enterprises 2019. See full book for sale on the books list.