402 THOMAS C. CHAMBERLIN 
of new compounds, new minerals, and possibly even new molecules 
and new atoms; (0) an increase of endothermic compounds as the - 
temperature increased; (c) the removal of liquefied material and its 
heat of liquefaction; as also (d) the self-heating radioactive sub- 
stances that helped to produce the liquidity. This process was 
essentially a metamorphic one, but in the deep interior the stresses 
and temperature rose to a much higher order than in the zone of 
observation, and the metamorphism is assumed to have been 
more radical.* 
39. Simple pressure experiments are incompetent to , determine 
the limit of self-compression in this broader sense. Such experi- 
ments cannot even cover the full range of metamorphic reorganiza- 
tion recorded in the observational zone. They are much less 
competent to set metes and bounds to the higher order of meta- 
morphism under immensely greater stress conditions. At best 
they can only indicate how much of the observed effect is to be 
assigned to simple mechanical compression and how much to 
metamorphism in the interest of higher density. 
4o. To set the new view into sharp contradistinction to the olf 
let it be noted that the planetesimal earth is looked upon as a 
profoundly metamorphic earth with a minor igneous accessory, 
while the traditional earth is commonly regarded as a profoundly 
igneous earth with a minor surficial metamorphic subsidiary. 
RESCRUTINY OF THE FORMATIVE PROCESSES 
The importance of the results of planetary comparison made it 
seem imperative to rescrutinize the whole chain of postulates that 
lies back of them. Chief among these were the tenets of the 
planetesimal hypothesis itself. This hypothesis was therefore 
reconsidered from the ground up. At the same time competing 
hypotheses were retested, for these lie, in a similar way, back of the 
older views of diastrophism, whether their authors are aware of it 
ornot. This restudy brought forth not only evidence confirmatory 
of previous views but supplementary considerations which need to 
be summarized here as part of the groundwork on which further 
study is to proceed. 
* The Origin of the Earth (1916), chap. ix, ‘‘The Inner Organization of the Earth,” — 
pp. 226-40. 
