I 
examination showed that several dif- 
ferent meteorite types were present, 
representing several distinct falls. The 
results of that examination have been 
amply confirmed by additional 
searches in the same region, in 1973, 
1974, 1975-76, and 1979-80, that 
have yielded more than 3,000 speci- 
mens in all. 
The early work on the Yamato me- 
teorites was reported at a meeting of 
the Meteoritical Society in Davos, 
Switzerland, in August 1973. William 
A. Cassidy of the University of Pitts- 
burgh, a scientist with long experience 
in the search for meteorites, who at- 
tended that meeting, was immediately 
struck by the evidence for some con- 
centrating mechanism — a process that 
would explain the occurrence of sev- 
eral different meteorite types in a 
small area — and deduced that special 
conditions unique to the Antarctic ice- 
cap must be responsible. He concluded 
that similar conditions should exist 
elsewhere in Antarctica. The success 
of subsequent expeditions led by- 
Cassidy to areas other than the 
Yamato Mountains has clearly dem- 
onstrated the validity of his thesis. 
Statistics on meteorite falls are im- 
perfect, since falls are unpredictable 
and many go unobserved. However, 
extrapolation from observations in 
densely populated regions indicate an 
average meteorite infall of one per 
million square kilometers per year, or 
about 500 a year for the entire planet. 
Since the oceans cover about 70 per- 
cent of the earth’s surface, only about 
150 meteorites a year fall on land 
and can be recovered. Because much 
The midnight sun illuminates the 
region south of Allan Hills, 
Antarctica, where many meteorite 
specimens have been found. 
63 
