Imaggeo on Mondays: Tertiary Flying Saucers

Polarized light photomicrograph of a thin section of a fossiliferous limestone from Lake Garda, Italy: Tertiary Flying Saucers. Credit: Bernardo Cesare (distributed via imaggeo.egu.eu)

Besides for the purposes of documenting my research, I like to take photos of rocks under the microscope also because of their aesthetic appeal. It’s an hidden, marvelous world.

These flying-saucer-looking objects are in fact the fossil skeletons of a Nummulites (the larger) and a Discocyclina (the one on top left), both belong to the phylum of Foraminifera. These single-celled organisms occupyied an important ecological niche of shallow and warm marine habitats during the Tertiary period, after the disappearance of dinosaurs. After their death, these variously and elegantly crafted, disk-shaped shells accumulated on the sea floor, forming thick piles of sediments, subsequently lithified into limestones.

Nummulite-bearing limestones are widespread around the Mediterranean. In Egypt they were used for the building of the pyramid of Gizah. In northeastern Italy these rocks were intensely quarried as ornamental stones since Roman times and used in villas, palaces and for statues by artists such as Palladio and Sansovino. This rock sample was collected for the project GardaLakeArtRock by my colleague Nereo Preto, at Nago, on the northern tip of Lake Garda (Italy, coordinates N.45°52’45.8″ E010°53’11.1″). The sampled rock formation is the Nago limestone, of medium-upper Eocene age (42-34 Ma). Width of view 5.4 mm.

Description by Bernardo Cesare, University of Padova, Italy

www.microckscopica.org

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