816 GEOLOGY 



in northern Europe, and extended in the southern part of the 

 continent. Non-marine formations have much representation 

 in this, as in most other post-Paleozoic systems. Some of the non- 

 marine formations are of brackish-water origin, and some of fresh. 

 The marine beds occifr chiefly along the Atlantic and Mediterranean 

 coasts. The marine Miocene of Germany, Holland, and Belgium, 

 is largely buried beneath glacial drift, and the exposed parts of 

 the system are chiefly of non-marine origin. They include coal 

 and tuff, besides the commoner clastic sediments. Thick conglom- 

 erates (3,900-5,900 feet) of early and Middle Miocene age are found 

 along the north base of the Alps (Rigi), and tell something of tl it- 

 relief of the Alpine region at the time. 



From the shallow epicontinental sea which covered par 1 

 Belgium and France, there may have been a sea connection by way 

 of the Garonne, with the Mediterranean along the northern 1 

 of the Pyrenees. The strait of Gibraltar is thought to have boon 

 closed, and southern Spain joined to Africa; but there were perhaps 

 straits across Spain, as across southern France, connecting the 

 Atlantic with the southern sea. 



Southern Europe appears to have been an extensive archipelago, 

 the plateau of Spain, parts of the Pyrenees, the Alps, and the < 

 pathian Mountains, and portions of adjacent lands, being island-. 

 The sea of southern Europe was expanded eastward far beyond the 

 limits of the present Mediterranean. Late in the period, there 

 was a notable withdrawal of the sea from the land. 



The Miocene formations include all the ordinary sorts of sed- 

 imentary rocks common to marine and non-marine deposits, 

 latter include not a little limestone of fresh-water origin, made 

 partly from the secretions of algae'. The system has great develop- 

 ment in Italy, where it is said to attain a thickness of nearly 6,< 

 feet. 



In spite of the wide sway of the southern sea of Europe, the 

 Miocene formations do not appear at the surface in great 

 though found in all countries bordering the Mediterranean, both 

 in Europe and Africa. In most of these countries, the lower fo: 

 tions are of marine origin, and the upper of brackish- or t> 

 water origin. They occur in Syria, but not in Arabia and IV 



