Tertiary and quaternary strata in geology named by Italian mining expert Giovanni Arduino

In 1760, the Italian mining expert Giovanni Arduino (1714-1795) laid out a scheme for classifying the strata of the Italian Alps, which he separated in the three main groups he called Primary, Secondary, and Tertiary [1,2]. A fourth strata, called Quaternary, was later added. Alan Cutler outlines Arduino's classification approach, following the stratigraphic principle formulated by Nicolaus Steno [2]:

The Primary strata, at the bottom of the pile, were tilted and lacked fossils. Next, were the Secondary strata, which were tilted but had fossils in them. On top were the Tertiary strata, which were horizontal and also contained fossils. He added a fourth class, Quaternary, for the sands and gravels that covered the bedrock in the nearby Po River Valley.

Today, scientists name the Primary and Secondary strata and the corresponding eras on the geologic time scale Paleozoic (about 540 to 250 million years ago) and Mesozoic (about 250 to 65 million years ago). Arduino's Tertiary and Quaternary divisions still stand [2]. The latter two are the main sub-divisions of the Cenozoic, spanning from the end of the Cretaceous (the last period in the Mesozoic) to the present [3].

Keywords: geology, stratigraphy, geologic time scale, natural history, terminology

References and more to explore
[1] Giovanni Arduino [www.strangescience.net/arduino.htm].
[2] Alan Cutler: The Seashell on the Mountaintop. Dutton (Penguin Group), New York, 2003; page 196.
[3] Introduction to the Cenozoic - 65 Million Years to the Present [www.ucmp.berkeley.edu/cenozoic/cenozoic.html].