5S HISTORY OF GEOLOGY AND PAL/EONTOLOGY. 



recurrent groups in the rock-succession, and he treated them 

 as "suites" or series, characteristic of each successive epoch 

 in the earth's history. Largely following the precedent of 

 Bergman, who had distinguished four principal rock-formations, 

 Werner erected five so-called formation-suites in his chrono- 

 logical scheme of the rocks : 



5. Volcanic rocks, sub-divided into true volcanic (lava, 

 volcanic scoriae and ashes, pepperino, tuff) and pseudo- 

 volcanic rocks (burnt clay, jasper, polishing-stone, slag). 

 4. 7'he transported or derivative rocks with the formations 

 nagelflue, sand, clay, pebbles, calcareous tufa, bitu- 

 minous wood, soapstone, aluminous earth, etc. 

 3. The Fiotz rocks with the formations old sandstone, coal, 

 old Flotz limestone, the ore-bearing or "Zechstein" 

 rocks, bituminous lignite, Muschelkalk, freestone and 

 chalk, basalt, pitch-coal, brown-coal, etc. 

 2. The transitional rocks with the formations clay-slate, 

 crystalline schist, greywacke, transitional greenstone, 

 gypsum and the first organic remains. 



i. The primitive rocks with the formations granite, gneiss, 

 mica schist, slate, primitive greenstone and limestone, 

 quartzite, hornblende schist, porphyry, serpentine, 

 chlorite and talc schist, primitive gypsum, etc. No 

 organic fossil remains. 



According to Werner, the primitive rocks originated during 

 the first chaotic period of the earth before the existence of 

 organic creatures, by chemical crystallisation of rock-material 

 from an aqueous solution. In the transitional period, the slates 

 and shales were held to represent chemical precipitates ; the 

 greywackes to have been mechanical deposits. During the 

 accumulation of the Flotz series, periods of disturbance 

 alternated with periods of quiet deposition ; the waters 

 frequently receded from land areas, and again inundated the 

 young continents. These varying conditions continued during 

 the succeeding epoch of active transportation, and finally gave 

 place to an epoch of violent volcanic outbreaks, the immediate 

 cause of which Werner believed to be the ignition of deposits 

 of coal in the earth's crust. 



Werner's practical knowledge of mining methods served him 

 in good stead when he came to study the strike and dip and 

 relative position of the rocks from a scientific point of view. 

 His application of more exact methods in taking field observa- 



