The Student's Elements of Geology Part 11

9. Old Red Sandstone.)

In another diagram (Figure 85), a real section of the geological formations in the neighbourhood of Bristol and the Mendip Hills is presented to the reader, as laid down on a true scale by Professor Ramsay, where the newer groups 1, 2, 3, 4 rest unconformably on the formations 5, 6, 7 and 8. At the southern end of the line of section we meet with the beds No. 3 (the New Red Sandstone) resting immediately on Nos. 7 and 8, while farther north as at Dundry Hill in Somersets.h.i.+re, we behold eight groups superimposed one upon the other, comprising all the strata from the inferior Oolite, No. 1, to the coal and carboniferous limestone. The limited horizontal extension of the groups 1 and 2 is owing to denudation, as these formations end abruptly, and have left outlying patches to attest the fact of their having originally covered a much wider area.

In order, therefore, to establish a chronological succession of fossiliferous groups, a geologist must begin with a single section in which several sets of strata lie one upon the other. He must then trace these formations, by attention to their mineral character and fossils, continuously, as far as possible, from the starting-point. As often as he meets with new groups, he must ascertain by superposition their age relatively to those first examined, and thus learn how to intercalate them in a tabular arrangement of the whole.

By this means the German, French, and English geologists have determined the succession of strata throughout a great part of Europe, and have adopted pretty generally the following groups, almost all of which have their representatives in the British Islands.

ABRIDGED GENERAL TABLE OF FOSSILIFEROUS STRATA.

1. RECENT.-- POST-TERTIARY.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

2. POST-PLIOCENE.-- POST-TERTIARY.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

3. NEWER-PLIOCENE.-- PLIOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

4. OLDER PLIOCENE.-- PLIOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

5. UPPER MIOCENE.-- MIOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

6. LOWER MIOCENE.-- MIOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

7. UPPER EOCENE.-- EOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

8. MIDDLE EOCENE.-- EOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

9. LOWER EOCENE.-- EOCENE.-- TERTIARY OR CAINOZOIC.-- NEOZOIC.

10. MAESTRICHT BEDS.-- CRETACEOUS.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

11. WHITE CHALK.-- CRETACEOUS.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

12. CHLORITIC SERIES.-- CRETACEOUS.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

13. GAULT.-- CRETACEOUS.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

14. NEOCOMIAN.-- CRETACEOUS.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

15. WEALDEN.-- CRETACEOUS.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

16. PURBECK BEDS.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

17. PORTLAND STONE.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

18. KIMMERIDGE CLAY.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

19. CORAL RAG.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

20. OXFORD CLAY.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

21. GREAT or BATH OOLITE.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

22. INFERIOR OOLITE.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

23. LIAS.-- JURa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

24. UPPER TRIAS.-- TRIa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

25. MIDDLE TRIAS.-- TRIa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

26. LOWER TRIAS.-- TRIa.s.sIC.-- SECONDARY OR MESOZOIC.-- NEOZOIC.

27. PERMIAN.-- PERMIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

28. COAL-MEASURES.-- CARBONIFEROUS.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

29. CARBONIFEROUS LIMESTONE.-- CARBONIFEROUS.-- -- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

30. UPPER DEVONIAN.-- DEVONIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

31. MIDDLE DEVONIAN.-- DEVONIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

32. LOWER DEVONIAN.-- DEVONIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

33. UPPER SILURIAN.-- SILURIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

34. LOWER SILURIAN.-- SILURIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

35. UPPER CAMBRIAN.-- CAMBRIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

36. LOWER CAMBRIAN.-- CAMBRIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

37. UPPER LAURENTIAN.-- LAURENTIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

38. LOWER LAURENTIAN.-- LAURENTIAN.-- PRIMARY OR PALAEOZOIC.-- PALAEOZOIC.

TABULAR VIEW OF THE FOSSILIFEROUS STRATA,

SHOWING THE ORDER OF SUPERPOSITION OR CHRONOLOGICAL SUCCESSION OF THE PRINc.i.p.aL GROUPS DESCRIBED IN THIS WORK (CITING EXAMPLES).

POST-TERTIARY.

1. RECENT. Sh.e.l.ls and mammalia, all of living species.

BRITISH.

Clyde marine strata, with canoes (Chapter 10.)

FOREIGN.

Danish kitchen middens (Chapter 10.) Lacustrine mud, with remains of Swiss lake-dwellings (Chapter 10.) Marine strata inclosing Temple of Serapis, at Puzzuoli (Chapter 10.)