| Name: | Microbialite |
| Classification: | Chemical sedimentary rock, microbial boundstone |
| Mineral composition: | Calcite |
| Fossils: | thrombolytic microbialites |
| Location: | Giau Pass, Mount Cernera (46°28'22.0"N 12°04'30.1"E) |
| Formation: | San Cassiano formation |
| Era: | Lower Carnian (approximately 235 million years ago) |
| Depositional environment: | Carbonate substructure, microbial reef |
These coloured circles are almost certainly marine worm holes, and the dark mass from which they spring is an encrustation of calcite precipitated in bacterial mucilage.
It is a gruesome thought, but in the lower Carnian age (approximately 235 million years ago), the Dolomite seas were rich in mucilaginous bacteria; entire mountains such as the Saddle or Sassolungo are nothing less than gigantic castles of bacterial
encrustations, with a few other fossils (sponges, corals, the odd shell) that make a minimal contribution to the volume of the rocks.Today the situation is different. Environments such as those where these bacteria proliferated are now colourful coral reefs. We live in a fortunate time, and the Triassic sea, if we could see it as it was, would look like something from another planet.
GALLERY
