PROBABILITY OF METEORITES HAVING FALLEN 27 
A large meteor need not necessarily be an iron one, and we have a 
remarkable block of melilite-basalt in Cape Colony which has certain 
features that point to its possible meteoric origin. The occurrence 
is at the top of the Spiegel River Valley in Riversdale; the outcrop of 
the rock is about 100 feet in an east-and-west direction, and half 
as much across, though, as it is found at the top of a hill, and the sides 
are strewn with débris from it, it is hard to determine the exact size 
of the block; there are bands of harder and softer material in it which 
give the mass the appearance of being bedded, and the dip is some 15° 
to the southeast. It is surrounded on all sides by coarse, loose con- 
glomerates of Cretaceous age which show no disturbance whatever. 
Had the mass come up in a volcanic throat, one would have expected 
to see some evidence of the explosive force in the loose gravel, .or 
some lateral dykes or fume vents, but nothing of the sort could be 
found, and no other volcanic rocks occur within many miles. The 
view adopted by the Geological Survey? is that it is a volcanic pipe 
filled in, but that is simply because no similar blocks have been 
described with which to compare it whereas melilite-basalt ordinarily 
occurs in connection with volcanoes. 
If we turn to the moon whose surface being free from erosion and 
deposit should show clearly any marks made on it by the fall of 
meteorites, we find certain evidence which is highly suggestive. The 
craters which are scattered so freely over the moon’s surface were 
thought by Gilbert? and others to be due to the impact of meteors; 
that they were not so formed we gather from the following considera- 
tions. In some of the craters the floor or top of the lava column 
stands many hundreds of feet below the general level of the surface, 
but in others the floor is as much above that level. The internal 
walls of the craters show definite terraces like old strand lines which 
have been formed by the successive retreat of molten material within 
the volcanic chimney. The craters, especially the smaller ones, 
often lie upon definite lines of fissures like the volcanic fissures of Ice- 
land, an arrangement which would have been impossible had they 
been formed by the infalling of meteors. Lastly there is a regular 
t A. W. Rogers and E. H. L. Schwarz, Ann. Rept. Geol. Comm., 1898, Cape 
Town, 1900, p. 62. 
2G. K. Gilbert, Bull. Phil. Soc. Washington, XII, p. 241. 
