o* MIOCENE, OR MIDDLE TERTIARY. 



mals became more numerous, and more like those of our own 

 times ; then there existed a great number of mollusks, belonging to 

 species which still inhabit the seas of the present epoch. 



16. In England the miocene tertiary is represented by a thin 

 and variable heap cf gravelly strata, called the "crag formation,'* 

 which is divided into three parts. The lowest is called coralline 

 crag, because a great many coral remains are found in it ; the 

 next is the red crag, distinguished by its deep ferru'ginous stain ; 

 the uppermost is named Norwich, or mammali'fe rous crag, which 

 is of more recent origin than the red crag, and contains bones of 

 large mammals, and occasionally fresh-water shells. 



17. An extensive series of miocene beds occupies the whole 

 surface cf both shores of the Chesapeake Bay, a hundred miles 

 north and south, and fifty miles wide. A similar series occurs in 

 Virginia. The lowest beds of the Chesapeake series are argilla'- 

 ceous, and the uppermost are sandy ; both series abound in fossils, 

 and when met on the side of a river they are sometimes found to 

 consist of little else than shells and the remains of zo'ophytes, often 

 in a high state of preservation. 



18. The miocene tertiaries prevail extensively on the continent 

 of Europe in various river basins. They occupy a considerable 

 portion of the west of France, filling up the basins of the Loire 

 and Garonne ; they fill up also a great part of the valley of the 

 middle Rhine, and the whole of the great valley of Switzerland, 

 between the Alps and the Jura chain ; and from Switzerland they 

 extend towards the north-east, following the course and partly fill- 

 ing up the valley of the Danube. From point to point they may 

 here be traced spreading out into extensive series near Vienna, and 

 in Styria, and occurring again in the plains of Hungary ; they are 

 also found in Poland and Russia ; they appear both in northern 

 and southern Italy, and on the shores and islands of the Mediterra- 

 nean. 



19. The miocene beds of the basin of the Loire are chiefly de- 

 veloped near the city of Tours, and in the Touraine district, where 

 they consist for the most part of broken shells ; these beds, how- 

 ever, sometimes afford a building stone, the comminuted shells 

 being mixed with sand and gravel, and cemented by calcareous 

 matter. In Switzerland there is a series of tertiary sandstones of 

 the miocene period ; and between the lakes of Geneva and Lu- 



15. What U remarked of the miocene period, as respects animals ? 



16. How are the miocene beds represented in England ? What is coral 

 line crag ? What is red crag? What is Norwich crag? 



1 7. In what part of the United States do we find examples of miocene 

 beds ? 



18. Where do we find miocene beds in Europe ? 



19. What is the nature of the miocene beds in Switzerland? What > 

 molasse " 



