When we step on the soil of our Earth we somehow take it for granted that everything has always been as we see it. In fact, our planet has evolved over millions of years and each change has left marks that teach us fundamental things. An example? The most precious gold nails which are well “planted” in the soil.
And not just any soil: the golden nails are planted in GSSPacronym for Global Stratotype Section and Point. Their presence makes the places where they are found interesting internationally, both for the scientific community and for the curious who want to know more about the Earth.
GSSP and Gold Nails: What Are They Really?
To understand the importance of gold nails, you must first understand what GSSPs are specifically. Explaining it very simply, they are gods rocky successions that make up geosites of fundamental importance to define the chronological evolution of the Earth. Why are they relevant? Because within them there is a specific point that it represents two floors of the chronostratigraphic scale global standard
In a nutshell, these geosites present, one next to the other, a point that defines a clear limit between formations of two different geological ages and which, compared to the rest of the world, contains more chemical, geomagnetic, radiometric and palentological information of the ages it defines. Precisely this limit is called Golden Spike, Golden Nailand in some parts of the world a golden nail has been planted to signal it.
The standards on GSSPs and gold nails
Clearly, finding these essential points for planet Earth is anything but easy. To be clear, the internationally agreed standards stipulate that gold nails can be planted only in the points where there is a clear division between an upper and a lower stage on the geological time scale. The GSSPs (and consequently the gold nails) are based, however, in principle on paleontological changesbut sometimes they also describe faunal transitions.
The identification remains relative to the actual impact that particular point has on studies concerning terrestrial evolution. To be clear, scientists have established that a GSSP must also be defined on the basis of a precise primary marker (for example the first detection of a specific fossil) and a series of secondary markers (fossils, chemical inversions).
In addition, even if the thicknesses of the various GSSPs are variable, it cannot be excessively thin nor too thick e it must not show any alterations related to tectonic movements. It must also be accessible and protected (possibly included within a natural search). Stringent standards? Probably, and it is perhaps also for this reason that in the world, so far, only eighty have been identified.
Where are the gold nails found?
Where, then, are these golden nails? They are actually scattered all over the world. In Italy, however, there are 12. The first is found in Calabriain the province of Crotone (Vrica) and dates back to the Pleistocene, while the next three are found in Sicily, precisely in Gela, Porto Empedocle and Eraclea Minoa, and date back to the Pleistocene and Pliocene. Dating back to the Miocene, they are instead, those found in Marchein Ancona, and in Piedmontin Carrosio.
In the‘Central Apennines and again ad Ancona there are two dating back to the Oligocene, while in the Venetian Pre-Alps and again in the Central Apennines there are two Golden Spikes dating back to the Eocene. Finally, in the Dolomites and in the Lombard Prealps there are gold nails dating back to the Triassic.