DIASTROPHISM AND THE FORMATIVE PROCESSES 409 
59. The size of planetesimals is not really important in con- 
sidering the heating effects of their infall, for what might be gained 
by their aggregation into large sizes would be lost by the lessened 
frequency of their infall, but to round out the inquiry a study was 
made of the effects of the infall of supposedly large bodies. 
6o. The great pit and the scattered material of the famous 
Meteor Crater (Coon Butte), Arizona, the greatest of accessible 
examples of its kind, show that the impact of a large body— 
probably meteoritic or cometic—caused extremely little melting 
but yet great excavation, much upturning and wedging aside of 
strata and wide scattering of débris. Its lesson is that the impact 
of such bodies converts their energy of motion mainly into new 
forms of mechanical work, and very subordinately into melting.’ 
- 61. On the supposition—not in fact accepted—that the craters 
of the moon are pits formed by infalling bodies, the proper inference 
from the observable effects is the same as that from Meteor Crater. 
The steep-walled pits and the great radiating lines of débris are 
direct evidence of great mechanical effects. The lofty walls of the 
pits show no signs of the collapse that should attend great melting. 
The evidence of lava flows, in proportion to the number and size of 
the craters, is not remarkable on the most favorable interpretation. 
The level tracts, interpreted as lava, may be merely débris plains. 
The lunar Alps, Apennines, and other mountain ranges of the moon 
imply at least a crust stout enough to sustain such great elevations. 
Nothing observable definitely implies a holo-molten state.’ 
MELTING EFFECTS OF PLANETESIMAL INFALL 
62. The planetary nuclei undoubtedly picked up some planetesi- 
mals that had wide-ranging orbits, but the larger portion specially 
related to the earth were distributed in the form of a ring around 
the sun about 55,000,000 miles in breadth, 58,000,000 miles in 
depth, and 292,000,000 miles in length. All these planetesimals 
had their own independent orbits, and were sustained by their 
own revolutionary energy. Their condition was antithetical 
to the collisional and collapsing habit of molecules in a gaseous 
1“The Testimony of Coon Butte or Meteor Crater,” zbid., pp. 686-89. 
2“The Questionable Intimations of the Craters of the Moon,” zb7d., pp. 690-94. 
