THE EOCENE PERIOD 801 



Amber is fossilized resin, apparently from certain varieties of conif- 

 erous trees. Its original position in the Baltic region appears to 

 be in certain glauconitic beds of a clayey nature, but parts of this 

 formation have been worn by the waves, and the amber distributed. 

 Some of that which finds its way into commerce is picked up on 

 the Baltic shore, while some is taken from the beds in which it was 

 originally entombed. One of the interesting features of the amber 

 is the fact that it frequently contains insects. The insects seem 

 to have alighted upon the resin while it was soft, and to have be- 

 come completely immersed in it, and perfectly preserved. About 

 2,000 species have been found thus embedded. 



Considerable deformative movements made themselves felt in 

 Southern Europe at or about the close of the Oligocene, as in the 

 Balkan and Carpathian Mountains. 1 



Other continents. In other continents, the Oligocene has not 

 been generally differentiated, but it is known in northern Africa 

 and in Patagonia, 2 where it is partly marine and partly non-marine. 



THE LIFE OF THE OLIGOCENE 



The vegetation. The mixed evergreen and deciduous forests of 

 the Oligocene were similar to those of the Eocene, especially in 

 Europe, where palms continued to be abundant and varied, growing 

 even in north Germany. They seem to have become rare, however, 

 in the United States, for in the Florissant sediments, which are 

 rich in plant fossils as well as insects, palms are barely represented. 

 The Florissant fossils show a variety of angiosperms, widely 

 distributed through the several orders that are now found in the 

 latitude of the middle and southern states. 



The land animals. All the species of insects of the Florissant 

 beds 3 (over 700) are extinct. This seems to indicate that although 

 the types had all become modern, the species continued to change 

 with relative rapidity. Fish fossils are abundant in the same beds. 



1 Willis. Carnegie Institution Year book 4, 1905. 



2 Hatcher, See references to this region under Eocene, and especially 

 Geol. Mag., 1902, p. 136. 



3 The Tertiary Insects of North America, U. S. Geol. Surv. Ter., Vol. XIII, 

 1890; Mon. XXI and XL, U. S. Geol. Surv., 1893 and 1900. 



