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CHAPTER XVI. 



ON THE LOWER OR MORE ANCIENT TERTIARY STRATA. 



Formation of Tertiary Strata in Lakes or Inland Seas. — Lakes of North Ameri- 

 ca. Falls of Niagara. — Alternations of Marine and Fresh water Strata. — Ar- 

 rangement of the Tertiary Strata in the Paris Ba.sin. — Plastic Clay and Lon- 

 don Clay. — Geology of the lower Vale of the Thames. — Remains of Crocodiles 

 and the Nautilus in London Clay. — Molasse of Alpnach in Switzerland, with 

 Coal and Teeth of the Mastodon. — Calcaire Grassier, or Coarse Limestone of 

 the Paris Basin, supposed to be of the same Age as the London Clay. — Calcaire 

 Silicieux. — Gypsum and Gypseous Marl of the Paris Basin, containing Bones 

 of numerous extinct Species of Land Gluadrupeds. — Remarks on their discove- 

 ry and Organization by Baron Cuvier. — Marine Sandstone. — Millstone. — Up- 

 per Freshwater Formation. — Tertiary Strata in the Isle of Wight. — Crag of 

 IS^orfolk, its true Geological Position not determined. — Cliffs of Brighton. 



The name of tertiary has been given with much propriety to all 

 the strata that are more recent than the secondary ; the term is intel- 

 ligible, and onght not to be changed without sufficient reason ; the 

 introduction of new names in science serves only to perplex the stu- 

 dent, and is attended with no advantage. The name of supercreta- 

 ceouSj which has recently been applied to the tertiary strata, is pecu- 

 liarly inappropriate, as these strata may cover any of the lower rocks^ 

 and in Auvergne they may be seen resting on granite. If a neiv 

 name were necessary, post-cretaceous should have been chosen; as all 

 geologists are agreed, that the tertiary strata were deposited after 

 chalk. 



The tertiary formations comprise all the regular strata of lime- 

 stone, marl, clay and sandstone, that have been deposited after chalk. 

 It is only since the commencement of the present century that they 

 have attracted the notice of geologists : their true nature was before 

 unknown, or they were supposed to be local and alluvial depositions. 

 It is now discovered that tertiary formations are widely spread over 

 many parts of the globe, and are often of considerable thickness. 



The first circumstance which proved that the tertiary beds were 

 distinct from the secondary, was the discovery that many of these 

 beds contain the bones of the higher order of animals, as perfect in 

 their organization as any of the existing species of land quadrupeds. 

 The tertiary beds were farther remarkable, for presenting frequent 

 alternations of beds, containing the remains of marine animals, with 

 other beds that contain exclusively the remains of land animals, and 

 plants, and fresh water shells : hence the latter beds were denomina- 

 ted fresh water formations. A more accurate examination of the 

 secondary strata, has since been discovered, that fresh water forma- 

 tions occur also among the more ancient strata, but their characters 



