IV. Cenolithic group, or cenozoic (tertiary) group of strata : XII. Pliocene (neo-tertiary) : 34. Arverne : Upper pliocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : XII. Pliocene (neo-tertiary) : 33. Subapennine : Lower pliocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : XI. Miocene (middle tertiary) : 32. Falun : Upper miocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : XI. Miocene (middle tertiary) : 31. Limbourg : Lower miocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : Xb. Oligocene (old tertiary) : 30. Aquitaine : Upper oligocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : Xb. Oligocene (old tertiary) : 29. Ligurium : Lower oligocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : Xa. Eocene (primitive tertiary) : 28. Gypsum : Upper eocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : Xa. Eocene (primitive tertiary) : 27. Coarse chalk : Middle eocene. IV. Cenolithic group, or cenozoic (tertiary) group of strata : Xa. Eocene (primitive tertiary) : 26. London clay : Lower eocene. III. Mesolithic group, or mesozoic (secondary) group of strata : IX. Chalk (cretaceous) : 25. White chalk. : Upper cretaceous. III. Mesolithic group, or mesozoic (secondary) group of strata : IX. Chalk (cretaceous) : 24. Green Sand : Middle cretaceous. III. Mesolithic group, or mesozoic (secondary) group of strata : IX. Chalk (cretaceous) : 23. Neocomian : Lower cretaceous. III. Mesolithic group, or mesozoic (secondary) group of strata : IX. Chalk (cretaceous) : 22. Wealden : Weald-formation. III. Mesolithic group, or mesozoic (secondary) group of strata : VIII. Jurassic : 21. Portland : Upper oolithic. III. Mesolithic group, or mesozoic (secondary) group of strata : VIII. Jurassic : 20. Oxford : Middle oolithic. III. Mesolithic group, or mesozoic (secondary) group of strata : VIII. Jurassic : 19. Bath : Lower oolithic. III. Mesolithic group, or mesozoic (secondary) group of strata : VIII. Jurassic : 18. Lias : Liassic. III. Mesolithic group, or mesozoic (secondary) group of strata : VII. Triassic : 17. Keuper : Upper triassic. III. Mesolithic group, or mesozoic (secondary) group of strata : VII. Triassic : 16. Muschelkalk : Middle triassic. III. Mesolithic group, or mesozoic (secondary) group of strata : VII. Triassic : 15. Bunter : Lower triassic. II. Paleolithic group, or paleozoic (primary) group of strata : VIb. Permian : 14. Zechstein : Upper permian. II. Paleolithic group, or paleozoic (primary) group of strata : VIb. Permian : 13. Neurot sand : Lower permian. II. Paleolithic group, or paleozoic (primary) group of strata : VIa. Carboniferous (coal-measures) : 12. Carboniferous sandstone : Upper carboniferous. II. Paleolithic group, or paleozoic (primary) group of strata : VIa. Carboniferous (coal-measures) : 11. Carboniferous limestone : Lower carboniferous.