INTRODUCTION. 35 



Targioni Tozetti, of Tuscany, occupied himself with the fossil 

 lenticles (Nummutitcs) of Casciano and Parlascio, which he 

 took for corals, and also with the fossil remains of land mam- 

 malia that are distributed in the valley of the Arno, in Val di 

 Chiana, and Ombrosa. Targioni showed conclusively that the 

 mammalia had lived in these valleys, and had not been 

 carried there by any diluvial catastrophe, or brought by the 

 Carthaginians. 



To Christopher Packe we are indebted for the first geo- 

 logical map of a part of England in his work, A New 

 Philosophical-Chorographical Chart of East Kent^ published in 

 1743. The map embraces a district of 32 English miles in 

 the east of Kent, and the descriptions in the text are illustrated 

 in the map by special signatures and lines. 



Lehmann 1 had an ample knowledge of the minerals 

 and fossils that occur in the rocks of Prussia. His work, 

 Versuch einer Geschichte des Flotzgebirge (Berlin, 1756), con- 

 tains a wealth of carefully observed data, and an elaborate 

 statement of his ideas about the origin and composition of the 

 earth's crust. Lehmann accepts a universal deluge, which V 

 dissolved or carried away in suspension much of the loose 

 surface material of the primeval mountains. The fine earth 

 and clay thus removed was precipitated as horizontal layers 

 on the sides and at the base of the mountains, and formed 

 the stratified deposits (Fidtzgcbirgc). As the waters receded, 

 these deposits, together with the remains of plants and animals 

 that had fallen upon the sea-floor, hardened into solid rock. 



Lehmann distinguished the primitive rocks from those of 

 derived origin by their greater height, and by the nature 0f the 

 veins or dykes (Ganggesteine) that occur in them. He did not, 

 however, differentiate between the mode of origin of the so- 

 called vein-rocks and the stratified systems. He thought the 

 vein material had also originated from water, but had been 

 laid down in disorder in the early periods of creation before 

 the universal deluge, so that it was vertically or diagonally 

 deposited, and contained few or no fossils. 



1 Johann Gottlob Lehmann was a teacher of mineralogy and mining in 

 Berlin. His writings extend over chemical, mineralogical, geological, and 

 mining subjects. In 1761 the Czarina Catherine elected him Professor 

 of Chemistry, and Director of the Imperial Museum at St. Petersburg, but 

 he died in 1767 from injuries caused by the explosion of a retort filled with 

 arsenic. 



