10. Upper white chalk. Marine limestone composed in part of decomposed corals. 11. Lower white chalk. 12. Upper green sand. 13. Gault. Dark-blue marl at base of chalk escarpment. Numerous extinct genera--conchiferous cephalopoda, etc. 14. Lower green sand. Species of shells, etc., nearly all distinct from those of Upper Cretaceous. F. Wealden. 15. Weald clay, of fresh-water origin. Shells of Pulmoniferous mollusca. 16. Hastings sand. Fresh water. Reptiles of, etc. 17. Purbeck beds. Limestone, calcareous slate, etc. Roots of trees; plants, etc. G. Oölite. 18. Upper Oölite. Portland building-stone, sand. 19. Middle Oölite. Oxford clay, dark-blue clay. Large saurians. 20. Lower Oölite. Preponderance of ganoid fish. Plants chiefly cycads, conifers, and ferns. H. Lias. 21. Argillaceous limestone, marl clay. Mollusca, reptiles, and fish analogous to the Oölitic. I. Trias. 22. Upper Trias. Red, gray, green, blue, and white marls, and sandstone, with gypsum. Batrachian reptiles. 23. Middle Trias. Compact grayish limestone, with beds of muschelkalk, of dolomite and gypsum. 24. Lower Trias. Plants different for the most part. IV. Primary. J. Permian. 25. Upper Permian. Yellow magnesian limestone. Organic remains both animal and vegetable, more allied to primary than to secondary period. 26. Lower Permian. Marl slate. Thecodont saurians, heterocercal fish, etc. K. Carboniferous. 27. Coal measures. Great thickness of strata of fluvio-marine origin, with beds of coal of vegetable origin, based on soils retaining roots of trees. Oldest of known reptiles. Sauroid fish. 28. Mountain. Carboniferous or mountain limestone. Limestone with marine shells and corals, etc. L. Devonian. 29. Upper Devonian. Yellow sandstone, paving and roofing stone. Tribe of fish with hard coverings. No reptiles yet known. 30. Lower Devonian. Gray sandstone. M. Silurian. 31. Upper Silurian. Tilestone. Oldest fossil fish yet discovered. Trilobites, etc. 32. Lower Silurian. Caradoc sandstone, etc. No land plants yet known. Footprints of tortoise, etc. 33. Upper and Lower Cambrian. SYNOPSIS. Post-Tertiary. } } Pliocene. } Tertiary or Cainozoic. } Miocene. } } Eocene. } } Mesozoic. } Cretaceous. } } Jurassic. } Secondary or Mesozoic. } Triassic. } } Permian. } } Carboniferous. } } Devonian. } Primary or Paleozoic. } Paleozoic. Silurian. } } Cambrian. } }