The Ammonites are largely utilised in the case of the Mesozoic strata for separation of these strata into zones, each zone being characterised by some species of Ammonite, and the researches of Mojsisovics have proved that this zonal subdivision, long adopted for Jurassic rocks, is also applicable to those of Triassic age[99]. He gives the following table of the classification of the Triassic rocks of the Mediterranean Province, which is reproduced, as it is founded upon Palæontological evidence, and will probably be widely adopted.
[99] von Mojsisovics, Dr E., "Faunistische Ergebnisse aus der Untersuchung der Ammoneen-faunen der Mediterranen Trias." Abhandl. der k. k. Geologisch. Reichsanstalt, VI. Band 2 Abtheilung. Vienna, 1893.
| Series | Zonal Divisions | |
| Rhætic | 1. Zone of Avicula Contorta | |
| Juvavic | Upper Juvavic Middle Juvavic Lower Juvavic | 2. Zone of Sirenites Argonautae 3. Zone of Pinnacoceras Metternichi 4. Zone of Cyrtopleurites bicrenatus 5. Zone of Cladiscites ruber 6. Zone of Sagenites Giebeli |
| Carnic | Upper Carnic Middle Carnic Lower Carnic | 7. Zone of Tropites subbullatus 8. Zone of Trachyceras Aonoides 9. Zone of Trachyceras Aon |
| Noric | Upper Noric Lower Noric | 10. Zone of Protrachyceras Archelaus 11. Zone of Protrachyceras Curionii |
| Muschelkalk | Upper Muschelkalk Lower Muschelkalk | 12. Zone of Ceratiles trinodosus 13. Zone of Ceratiles binodosus |
| Buntsandstein | Werfener Schichten | 14. Zone of Tirolites Cassianus |
THE JURASSIC SYSTEM.
The Jurassic rocks were formerly separated on account of differences of lithological character into Oolites and Lias, but it was apparent that the Oolites were more important than the Lias, and a fourfold division was made into:—
| Upper or Portland Oolites Middle or Oxford Oolites | = Malm | |
| Lower or Bath Oolites Lias. | = Dogger |