474 Hevietcs — Genesis- Paleozoic and Mesozoic-Cenozoic. 



The term * Comanclieau ' is ajtplied to the Lower Cretaceous, to 

 incliule eras from the European Weahlen to Cenomanian ; the Upper 

 or true Cretaceous being- limited to the European Turonian. 

 Senonian, and Danian. The Cretaceous includes the Laramie^ 

 Series, with sandstone, shale, and coal, also other divisions of clay, 

 greensand, and chalk. It has yielded a remarkable assemblage o t" 

 vertebrates, especially Saurians (including sea serpents), and birds. 



The Cenozoic era is divided into Tertiary (Eocene to Plioceub) 

 and Quaternary (Pleistocene or Glacial, and Eecent or Human). 

 Interesting accounts are given of the Eocene and Oligocene faunas 

 and floras. As a rule, the Oligocene has not been differentiated from 

 Eocene in North America, but reasons are given to render the 

 division desirable. It is remarked that pronounced provincialism 

 was inaugurated in the Oligocene, and continued throughout the 

 remainder of the Cenozoic era. The correspondences between the 

 faunas of the western and the eastern sides of the Atlantic during 

 the Miocene period appear to have been " due partly to inter- 

 migration and partly^ to parallel evolution." As pointed out by Dall, 

 the Miocene fauna of North Germany compares well with that of 

 Maryland, while the Mediterranean Miocene is closely allied to the 

 more tropical fauna of the Duplin Beds of the Carolinas. The 

 history of the land animals in Tertiary times is full of interest. 



The giants of the Pliocene period were the Proboscideans. " The 

 mastodons seem to have occupied all the continents during the 

 Pliocene, but it is doubtful whether the elephant reached the 

 American continent before the Pleistocene." There must have been 

 migratory routes between Eurasia and America, but there are out- 

 standing problems as to the extent and continuity of the connections 

 at the north-west and north-east. 



The Pleistocene is regarded as of shorter duration than the average 

 geological period. " Ice-sheets spread over six or eight million 

 square miles of the earth's surface." More than half of this area- 

 was in North America, and more than half of the remainder lay in 

 Europe. The authors remark that " it is not strange that the glacial 

 theory was resisted for half a century, though the iceberg and other 

 glacio-natant hypotheses urged in its stead seem no more credible, 

 and far less adequate. But the cumulative force of a vast mass of 

 evidence, rigorously scrutinized under the promptings of this critical 

 and reluctant attitude, has become overwhelming, and the days of 

 reasonable doubt are passed." That there was a succession of ice- 

 invasions due to fluctuation in the actual limits of the large masses 

 of land-ice, the temporary retreats being accompanied by great 

 floods arising from the melting of the ice, is held by the authors 

 to be borne out by the careful studies of later years ; but geologists 

 are not agreed on this part of the subject. " It is not yet known 

 bow far the ice retreated in the intervals between the advances," 

 and consequently there are differences of opinion " respecting the 

 estimate to be put upon the importance of the interglacial intervals." 

 In connection with this subject Mr. Lamplugh's I'ecent address to 

 Section C of the British Association at York will be read with 

 interest. 



