A short section of coast displays an amazing diversity of geological features in rocks of Carboniferous age (about 335 million years old)
South of St Andrews, the coastal path leads to a cornucopia of geological interest. On the foreshore, along a 2km long stretch of the coast, the rock layers are bent into a variety of shapes – these are particularly visible at low tide and represent a dramatic period in the area’s geological history.
Layers of sandstone, mudstone, limestone and coal were laid down in the early Carboniferous when this part of Scotland lay to the south of the Equator. Then there was a period of deformation in the late Carboniferous – earthquakes and compression resulted in a landscape cracked and twisted under pressure. The folds in the sedimentary rocks are clearly visible today, with anticlines, synclines and dome structures found all along the coastline. From the cliff path, the anticlines and synclines are laid out on the shore below in several localities. The horizontal layers were pushed from both sides, rippled like a wrinkled carpet, and later tilted. Subsequently the top layers were gradually eroded away, exposing waves of alternating rocks which are visible at low tide.
Further to the east, the nature of the coastline changes and you can find three sea stacks, part of a volcano which erupted about 295 million years ago and punched through the pre-existing rocks. The eastern stack is called the Rock and Spindle, an area of ash containing blocks of other rocks, and a central column made from basalt within the volcano vent. As the basalt cooled, it formed columns in a radial form known as the “Spindle” because it resembles a spinning wheel.
This area is also rich in fossils, including trackways that tell us about the animals that were walking across mud and sand close to the Equator as these sedimentary rocks formed. In an inaccessible cliff near St Andrews are preserved the footprint casts of a Eurypterid, a giant six-legged sea “scorpion” about two metres long that walked across a sandy plain near the sea, dragging its tail. A replica of the trackway is on display at the Museum of the University of St Andrews (MUSA). Near Boarhills, an outcrop of sandstone reveals a pitted surface which represents the footprints of a Myriapod (giant millipede) named Arthropleura. The tracks are about 20cm wide. There are also splendid exposures of fossil tree roots (Stigmaria) showing a radial distribution from Lepidodendron trees.
Text contributed by Richard Batchelor
Find out more
Forsyth, I.H., & Chisholm, J.I. (1977). The Geology of East Fife. Mem. Geol. Surv. UK. (HMSO).
MacGregor, A.R. (1996). Fife and Angus Geology – an excursion guide. (Pentland Press).
Pearson, P.N. 1992. Walking traces of the giant myriapod Arthropleura from the Strathclyde Group (Lower Carboniferous) of Fife. Scottish Journal of Geology 28, 127-133.
Whyte, M.A. 2005. A gigantic fossil arthropod trackway. Nature 438, 576.
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