278 REPORT OF NATIONAL MUSEUM, 1904. 



The appearance in hook form of Prof. Jeremiah Van Rensselaer's 



lectures on geology, as delivered before the New York Athenaeum in 



L825, gives us an opportunity of judging of the condition of science 



at that date, such as was ottered a few years earlier bv 



Van Rensselaer's 



Lectures on Geology, Alitchill s Observations. 



1825. T7 t» i i ..... 



Van Rensselaer was not so much an original investi 

 gator as a student and teacher; hence the inference 1 is fair that his 

 work gives us a summary of existing knowledge rather than the details 

 of his own observations or his individual views. He reviewed the 

 opinions of the cosmogonists and theorists from Burnett, in 1680, 

 down to Werner and Mutton, and referred to the work of his prede- 

 cessors and contemporaries in America, summing up with conclu- 

 sions condensed from Cuvier's Observations, to the effect that, first, 

 the sea had, at one period or other, not only covered all our plains, but 

 remained there 1 for a long time in a state of tranquillity; second, that 

 there had been at least one change in the basin of the sea which pre- 

 ceded the present one; third, that the particular portions of the earth 

 which the sea had abandoned by its last retreat had been laid dry once 

 before and had at that time produced quadrupeds, birds, plants, and 

 all kinds of terrestrial productions; and that it had been reinundated by 

 the sea, which had since retired and left it to the possession of its own 

 proper inhabitants. These facts, which had been proven through 

 geological evidence, he regarded as supporting the accounts of Moses, 

 both agreeing, first, in the prevalence ever everything else of water 

 at the time of the creation; second, in the subsequent separation of 

 the land from the water; and, third, in the eruption of the sea over the 

 continent, the last corresponding to the Noachian deluge. 



Van Rensselaer recognized the value of fossils in proving the iden- 

 tit} T of geological horizons, also the fact that organic remains have 

 been deposited in successive generations and in such order that those 

 of one bed bear a certain connection to each other and exhibit certain 

 distinctive points differentiating them from those of earlier or later 

 deposits, and that the greater the distance between the deposits the 

 greater the difference between the contained fossils. This, 1 believe, 

 is the second recognition by an American author of a now well-estab- 

 lished principle. 



The tendency to make sweeping generalizations founded upon purely 

 local observations is noticeable in his writings, as in those of many of 

 his contemporaries. Thus, in describing the gneiss: 



It is the next rock to granite and occurs resting or lying upon it. When they are 

 both seen in the same mountain its ledge is always the lower of the two. Mountains 

 of gneiss are seldom so steep as those of granite, and the summits are not quite so 

 peaked. 



