PRELUDE TO DESCRIPTIVE GEOLOGY. 501 



Without attempting to assign to every important advance its author, I 

 shall briefly exemplify each of the modes of contributing to descriptive 

 geology which I have just enumerated. 



The study of organic fossils was first pursued with connexion and sys- 

 tem in Italy. The hills which on each side skirt the mountain-range 

 of the Apennines are singularly rich in remains of marine animals. 

 When these remarkable objects drew the attention of thoughtful men, 

 controversies soon arose whether they really were the remains of living 

 creatures, or the productions of some capricious or mysterious power 

 by which the forms of such creatures were mimicked ; and again, if 

 the shells were really the spoils of the sea, whether they had been car- 

 ried to the hills by the deluge of which the Scripture speaks, or 

 whether they indicated revolutions of the earth of a different kind. 

 The earlier works which contain the descriptions of the phenomena 

 have, in almost all instances, by far the greater part of their pages 

 occupied with these speculations ; indeed, the facts could not be studied 

 without leading to such inferences, and would not have been collected 

 but for the interest which such reasonings possessed. As one 

 of the first persons who applied a sound and vigorous intellect to 

 these subjects, we may notice the celebrated painter Leonardo da 

 Vinci, whom we have already had to refer to as one of the founders 

 of the modern mechanical sciences. He strenuously asserts the 

 contents of the rocks to be real shells, and maintains the reality of 

 the changes of the domain of land and sea which these spoils of the 

 ocean imply. "You will tell me," he says, "that nature and the 

 influence of the stars have formed these shelly forms in the moun- 

 tains ; then show me a place in the mountains where the stars at the 

 present day make shelly forms of different ages, and of different spe- 

 cies in the same place. And how, with that, will you explain the 

 gravel which is hardened in stages at different heights in the moun- 

 tains ?" He then mentions several other particulars respecting these 

 evidences that the existing mountains were formerly in the bed of the 

 sea. Leonardo died in 1519. At present we refer to geological 

 essays like his, only so far as they are descriptive. Going onwards 

 with this view, we may notice Fracastoro, who wrote concerning the 

 petrifactions which were brought to light in the mountains of Verona, 

 when, in 1517, ttey were excavated for the purpose of repairing the 

 city. Little was done in the way of collection of- facts for some time 

 after this. In 1669, Steno, a Dane resident in Italy, put forth his 

 treatise, De SoUdo intra Solidum nntumUter contento ; and the fol 



