GEOLOGICAL PERIODS. 



165 



QUARTIARY PERIOD 



(Diluvial and Alluvial 



Formations). 



TERTIARY PERIOD 



(Cainozoic Formations}. 



tions,* as the group of strata of one district of distribution and belong- 

 ing to one period are named, cannot be divided petrographically or 



* The following table may serve for a bird's-eye view of the geological periods 

 and their most important formations : 



f Recent Periods (alluvium, marine and fresh-water 



formations). 

 \Po8tplivcene or Diluvial Period (erratic boulders, 



glacial period). 

 'Pliocene Period (subappenine formations, bone sand 



of Eppelsheim, etc.) 

 i Miocene Period (Molasse, Tegel near Vienna, brown 



coal in North Germany, etc). 



Eocene Period { Fl ? sch > Nummulite formation 

 k ( of the Paris basin. 



(Maestricht strata, white chalk, 

 Cretaceous Period -j upper green sand. Gault, 

 lower green sand, Weald. 



fPurbeck strata, Portland stone, 

 Kimmeridge clay, Coral Bag, 



| Oxford clay, Great oolite, 

 Lower oolite, Lias (white, 



' brown, and black jura). 

 Keuper or upper new red sand- 

 stone, Muschelkalk (upper 

 Muschelkalk, gypsum and 

 anhydrite, Wellenkalk, Bun- 

 ter Sandstein). 



SECONDARY PERIOD 



(Mesozoic Formation}. 



SECONDARY PERIOD 



( Mesozuic Formations). 



Jurassic Period 



Triassic Period 



Permian 



Zechstein, Rothliegendes.- 

 lower new red sandstone. 



PALEOZOIC PERIOD / 



(PalcBuzoic Formation*). 



jCoal Measures of England, 

 Carboniferous Germany, and North 



Period \ America, Kulm formation, 



I Carboniferous limestone. 



Devonian Period (Spiriferenschiefer, Cypridinen- 

 schiefer, Stryngocephalenkalk, etc. old red sand- 

 stone.) 



Silurian Period (Ludlow, Wenlock, strata, etc.) 



Cambrian Period (slate, etc.) 



( Thonschiefer, Laurentian formations. Mica schist, 

 ( Older Gneiss formations. 

 According to Professor Kamsay the groups of formations in England have a 

 thickness of 72,581 feet, i.e., about 13| English miles ; that is, formations of the 



Paleozoic period have a thickness of 57.154 1 

 Secondary 13,190 V 72,584 feet 



ARCH^AN PERIOD 



Tertiary 



13,190 

 2.2JO J 



