THE TERTIARY SYSTEM. . 739 



between that mineral and peat. Lignitic beds occur in tertiary strata at Bovey Heatlifield 

 in Devonshire, and at the interesting locality of Alum Bay, in connection with amber. 

 They indicate the submergence of woods and forests, the amber, unquestionably a mineral 

 substance, derived from the vegetable kingdom, being a gum or gum-resin exuded by the 

 associated trees. Plastic clay, yielding the common pipe and potter's clay, and gypsum, 

 are extensively obtained from the London and Paris tertiaries, the latter forming, when 

 calcined and combined with water, the well-known plaster of Paris, so largely employed 

 in the arts. Magnesite, a stone essentially composed of magnesia, silex, and water, the 

 material of the meerschaum, occurs at various points around Paris, particularly in a hill 

 near Coulommiers, which has been cut to form a canal, exposing the interior structure. 

 The strata here consist of siliceous and calcareous marls, in which the magnesite shows 

 itself distinctly, as at w, in the section. 



Two of the largest cities in the world, and three of the most ancient capitals of Europe, 

 London, Paris, and Vienna, are situated upon tertiary strata. In England the geogra- 

 phical range of the system includes the north of the Isle of Wight, parts of Hampshire 

 and Dorset, the north of Kent and the Isle of Sheppey, a considerable area around and 

 west of the metropolis, with the eastern coast from the Thames into Holderness in York- 

 shire. No similar deposits have been recognised in Ireland, but in Scotland they occur 

 in the valley of the Clyde, and on the continent of Europe they are very extensively 

 developed. This appears from the following classification, which shows the relation of 

 the European tertiaries to existing seas : 



Connected with the North Sea, f The basin of London, Suffolk, Norfolk, Lincoln, and Yorkshire. The 

 or German Ocean. L north-east of France Belgium, Westphalia, Holstein, and Jutland. 



Connected with the English f The basin of Hampshire, including parts of Dorset and the Isle of 

 Channel. I Wight. The basin of Paris. 



Between the Baltic and Black Sea. The extensive sandy deposits of Prussia, Poland, Volhynia, and Wallachia. 



Connected with the Atlantic. The basin of the Garonne. 



{Tertiaries of Catalonia, 

 of the south coast of France and the valley of the Rhone, 

 of the northern sub-apennine regions, and of Sicily. 

 of the northern parts of Africa. 

 r The valley of the Rhine from Basle to Bingen. 

 e i j i J The interior basin of Bohemia. 



j The great hollow of the northern Swiss lakes, and the valley of the 

 L Danube, with the Moravian, Hungarian, and Transylvanian strata. 



The tertiaries occupy more than half the surface of Europe. They have likewise been 

 recognised along the southern roots of the Himalaya, while in America they embrace 

 nearly all the level region in the eastern part of the middle and southern United States. 

 In no English locality are they in association with igneous rocks ; but in Auvergne, in 

 Hungary, and Transylvania, in Tuscany and Campagna di Roma, and in Sicily, they are 

 found in connection with volcanic products. The external aspect of tertiary districts, 

 excepting those where disturbance from igneous action has taken place, is generally mono- 

 tonous, as in the great plains bordering on the Garonne, and the vast levels between the 

 Baltic and the Black Seas, but around London and Paris the scenery is varied, the strata 

 undulating with the subjacent chalk. 



The fossil contents of tertiary deposits, their most interesting feature, are of marine, 

 freshwater, and terrestrial origin. The beds containing them are frequently alternated 

 and mingled with each other in a confused and irregular manner. Rivers, lakes, land- 

 floods, and the sea, have contributed, therefore, to their formation, and we may conclude 

 generally that, during the tertiary era, the relations of land and sea were repeatedly 

 altered ; that the land was successively raised above the level of the ocean, and sunk 



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