Carboniferous
"During the 16th and 17th centuries, the town of Culross was a centre of the coal mining industry in Scotland, with the first coal mine in the world to extend under the sea in 1575. The mine worked what is now known as the Upper Hirst coal seam, with ingenious contrivances to drain the constant leakage from above. This mine was considered one of the marvels of the British Isles in the early 17th century, until it was destroyed in a storm, in 1625.
I believe this is the ruins of the pier that lead to one of the airshafts in the Firth of Forth that ventilated the mine and removed water seepage. In the distance can be seen the modern day energy descendants in the form of the Grangemouth Refinery, directly in front of the setting sun, and to the right, Longannet Power station, with their respective smoke columns."
