Aalenian
The Aalenian ( /ɑːˈliːniən/) is a subdivision of the Middle Jurassic Epoch/Series of the geologic timescale that extends from about 174.7 ±0.8 Ma to about 170.9 ±0.8 Ma (million years ago). It was preceded by the Toarcian and succeeded by the Bajocian.
| Aalenian | |||||||||
|---|---|---|---|---|---|---|---|---|---|
The Aalenian GSSP in Spain | |||||||||
| Chronology | |||||||||
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| Etymology | |||||||||
| Name formality | Formal | ||||||||
| Usage information | |||||||||
| Celestial body | Earth | ||||||||
| Regional usage | Global (ICS) | ||||||||
| Time scale(s) used | ICS Time Scale | ||||||||
| Definition | |||||||||
| Chronological unit | Age | ||||||||
| Stratigraphic unit | Stage | ||||||||
| Time span formality | Formal | ||||||||
| Lower boundary definition | FAD of Ammonites Leioceras opalinum and Leioceras lineatum | ||||||||
| Lower boundary GSSP | Fuentelsaz, Spain 41.1708°N 1.8333°W | ||||||||
| Lower GSSP ratified | 2000 | ||||||||
| Upper boundary definition | FAD of the Ammonites Hyperlioceras mundum, Hyperlioceras furcatum, Braunsina aspera, and Braunsina elegantula | ||||||||
| Upper boundary GSSP | Cabo Mondego, Portugal 40.1992°N 8.9042°W | ||||||||
| Upper GSSP ratified | 1996 | ||||||||
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