560 POPULAR SCIENCE MONTHLY. 



appearance of islands, sometimes in connection with vulcanism, some- 

 times as the result of other causes, thinkers were led to conceive the 

 possibility of large land-masses, or even continents, undergoing eleva- 

 tion and subsidence. Areas were known which the sea had invaded, 

 and other tracts were pointed out where submergence was plainly indi- 

 cated. Thus Xenophanes, in the sixth century B.C., and after him 

 Xanthus, Eratosthenes, Herodotus and others, not only entertained the 

 idea of continental subsidence, but interpreted fossil remains of marine 

 animals as evidence of former submergence. When we come to Aris- 

 totle, Posidonius and Strabo, we find that their opinions concerning 

 oscillations of the sea-level and other progressive changes of the earth's 

 surface are worthy of modern geologists. This phase of the subject 

 has been so ably treated by Lyell in his ' Principles of Geology,' by 

 Lasaulx, in his ' Geology of the Greeks and Eomans,' and more recent 

 writers, that it must be more or less familiar to all. That which is 

 important to remember, however, is that local manifestations of vul- 

 canism, dispersed over a wide region, and isolated examples of in- 

 constancy of the sea-level, should have been viewed from the uniformi- 

 tarian standpoint at a period so far antedating our own, should have 

 been reduced to a general system, and should have led to the framing 

 of hypotheses to account for them which have a singularly modern 

 aspect. One can not but marvel that some of the most difficult prob- 

 lems in geology were solved by rational methods, and in the main 

 accurately, by those ardent questioners of nature who often seem to 

 have grasped intuitively that which has cost the rest of the world cen- 

 turies of patient effort to rediscover. 



The limits assigned to the present article do not permit us to ex- 

 amine Eoman contributions to the study of vulcanism, interesting as 

 such an inquiry would be. Nor have we attempted in this sketch to 

 enumerate all of the lesser luminaries of Greek science who assisted, 

 either by accumulation of facts, or by cleverness in putting them to- 

 gether, toward a fuller understanding of important principles of 

 geology. Archelaus, Diogenes of Apollonia, Metrodorus of Chios, au- 

 thor of a famous ' Treatise on Nature,' Empedocles, whom a character- 

 istic but probably apochryphal narrative reputes to have perished in 

 Etna's crater, — these and various others have been passed over in 

 silence. Enough has been said, however, to indicate the general trend 

 of investigation and some of its fruitful conclusions. This brief 

 sketch will have succeeded in its purpose if any shall become interested 

 to pursue the subject independently in its details. Such retrospect has 

 not only a broadening value, but is well-nigh incumbent upon all who 

 would escape the fate against which Goethe so energetically warns us : 



Wer nieht von dreitausend Jahren 

 Sich weiss Rechenschaft zu geben, 

 Bleibt im Dunkeln, unerfahren, 

 Mag von Tag zu Tage leben. 



