INTRODUCTION. 93 



plants; then amphibians appear, and finally, whole skeletons 

 of terrestrial mammals and birds are imbedded in the sands 

 and clays. "Accordingly fragmentary historical testimony of 

 the beginnings and further stages of living organisms on the 

 face of the earth has been indelibly preserved in the suc- 

 cessive strata. It must be left to posterity, by means of 

 the united observations and efforts of many enquirers, to 

 solve the secrets of the earth's structure and read aright the 

 sequence of organic remains interred in the crust " (vol. ii., 

 p. 412). 



The periodicity in the recurrence of certain physical con- 

 ditions and the repetition of similar deposits were favourite 

 themes with Ebel. He showed that the same varieties of rock 

 occur repeatedly in the lateral zones of the Alps, and clearly 

 represent deposits gathered during different geological epochs. 

 Then he cited evidences, both from the central and lateral 

 Alpine zones, of recurrent paroxysms of the crust; these, in his 

 opinion, had been caused by the sudden transgression of the 

 ocean over terrestrial areas and the consequent devastation of 

 the land, erosion of valleys, and accumulation of fine and 

 coarse mechanical deposits at the base of the mountains. 



According to Ebel, the last and most violent inundations 

 had advanced in a direction from south-west to north-east, and 

 had transported the huge erratic blocks and the material of the 

 nagelflue and other pebble deposits to the northern band of 

 the Alps, and even as far as the North German plain. 



This same idea of periodicity led Ebel further astray when 

 he ventured into philosophical speculations. He compared 

 the body of the earth with a voltaic pile in spherical form, in 

 which a living element analogous with the electrical current 

 not only called forth the plant and animal kingdoms, but also 

 regulated the origin and arrangement of the minerals and 

 rocks. 



Such theoretical speculations were always kept apart from 

 the descriptive portion of Ebel's work, and scarcely affected 

 it, although they produced so unfavourable an impression 

 that they caused his work to be undervalued by his con- 

 temporaries. At the same time, Ebel's work undoubtedly 

 marks the high level of geological research as it was repre- 

 sented in the Alpine literature at the beginning of the century. 

 Unfortunately, Ebel had no deep insight into stratigraphical 

 details, and he lacked the genius to follow up the indications 



