GEOLOGICAL PERIODS. 



105 



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 period* 

 and their most important formations : 



[liecent Periods (alluvium, marine and fresh-wator 

 QUARTIARY PERIOD J formations) . 



(DilwoialandAllweial <p osip i iocene or #;],.;] /V/vW (erratic boulders, 



Formations). 



TERTIARY PERIOD 



(Citinozoie Formations) . 



glacial period). 

 Pliocene Period (subappenine formations, bone sand 



of Eppelsheim, etc.) 

 Miocene Period (Molasse, Tegel near Vienna, brown 

 coal in North Germany, etc). 



| Flysch, Nummulite formation 

 | of the Paris basin. 



^^ l Maestricht strata, white chalk. 



Cretaceous Period i upper green sand. Gault. 



lower green sand. Weald. 



Eocene- Period 



j 



SECONDARY PERIOD 



(Mesozoie For in at in 11} 



Period 



SECONDARY PERIOD 



(Mes,t;oic Formations). 



Purbeck strata, Portland stone, 

 Kimmeridge clay, Coral Rag. 

 Oxford clay. Great oolite, 

 Lower oolite, Lias (white, 

 brown, and black jura). 



SKeuper or upper new red sand- 

 stone, Muschelkalk (upper 

 ^, ...,,. ~ ...... Muschelkalk, gypsum and 



/ anhydrite, Wellenkalk, Bun- 

 ter Sandstein). 



J Zechstein, Bothliegend.es. 

 | lower new red sandstone. 



Perm in a 



Carboniferous 



Period 



PALAEOZOIC PERIOD ; 

 (Ptilfsozoie Formations). \ 



Coal Measures of England, 

 Germany, and North 

 America, Kulmformation, 

 Carboniferous limestone. 



Deronia-n Period (Spiriferenschiefer. Cypridiuen- 

 schiefer, Stryngocephalenkalk, etc. old red sand- 

 stone.) 



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



\Caiiilirinii Period (slate, etc.) 



(Thonschiefer, Laurentian formations. Mica schist. 

 ( Older Gneiss formations. 

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

 thickness of 72,584 feet, i.e.. about 13| Englishmiles ; that is, formations ( 

 Palaeozoic period have a thickness of 57,154] 

 Secondary - 13,190 72,,84 feet 



Tertiary 2.2JO ! 



PERIOD 



