Gyl­le­ne spiken*

On the east side of Hun­ne­berg, a gol­den spi­ke has been dri­ven into the wall. What is it doing there?

Well, the Earth’s histo­ry is divi­ded into vari­ous inter­vals that make up the geo­lo­gi­cal time sca­le. For examp­le, the Per­mi­an, Tri­as­sic and Juras­sic geo­lo­gi­cal peri­ods are each sub-divi­ded into epochs. Each geo­lo­gi­cal age has a refe­rence point somewhe­re in the world, and the gol­den spi­ke is one such refe­rence point! It was here that geo­lo­gi­cal histo­ry chang­ed from one stage to the next during the Lower Ordo­vici­an, 478 mil­li­on years ago. The gol­den spi­ke is an inter­na­tio­nal geo­lo­gi­cal refe­rence point for a geo­lo­gi­cal stage cal­led the Flo­i­an – named after the small vil­lage of Flo east of Hun­ne­berg. The Flo­i­an is dis­tin­gu­ished by a small fos­sil (a type of grap­to­li­te) that is found in the mountain here – a small mari­ne, worm-like cre­a­tu­re with four “arms” that first appe­a­red at this time. (Trut­h­ful­ly, the spi­ke has lost its gol­den sheen after a few years of expo­su­re to the ele­ments – but if you look care­ful­ly, you will see that it is still there!)