MOUNTAINS AND THEIR ORIGIN. 95 
in our knowledge to be filled up. All the at- 
tempts to represent the appearance of the earth 
in past periods by means of geological maps are, 
of course, but approximations of the truth, and 
will compare with those of future times when 
the phenomena are better understood, much as 
our present geographical maps, the result of re- 
peated surveys and of the most accurate meas- 
urements, compare with those of the ancients. 
Homer’s world was a flat expanse, surrounded 
by ocean, of which Greece was the centre. Asia 
Minor, the iEgean Islands, Egypt, part of Italy 
and Sicily, the Mediterranean and the Black Sea 
filled out and completed his map. 
Hecatosus, the Greek historian and geographer, 
who lived more than five hundred years before 
Christ, had not enlarged it much. He was, to be 
sure, a voyager on the Mediterranean, and had 
an idea of the extent of Italy. Acquaintance 
with Phoenician merchants also had enlarged his 
knowledge of the world ; Sardinia, Corsica, and 
Spain were known to him, and he was familiar 
with the Black and Bed Seas ; though an in- 
dentation on his map in the neighborhood of the 
Caspian would seem to indicate that he was 
aware of the existence of this sea also, it is not 
otherwise marked. 
Herodotus makes a considerable advance be- 
yond bis predecessors : the Caspian Sea has a 
