306 C.K LEE 
means a greater volume-increase, by perhaps 4o per cent., when pore- 
space is figured, on the basis of experimental determinations of pore- 
space of the different classes of sediments, again combined in the 
stated proportions. ‘There is still greater increase of volume if the 
substances remaining in solution, such as salts in the ocean, be cal- 
culated as solids. On the other hand, if only the residual materials 
from weathering are taken into account, not the chemical sediments, 
it may be shown that in spite of the increase in volume of certain 
minerals, the mineral volume of each of the principal rocks developed 
from the residual weathering materials has decreased. Volume- 
changes will be discussed in more detail in another article. 
In general, katamorphism means simplification, both chemical 
and mineralogical, sorting, segregation of like substances, increase of 
volume, hydration, carbonation and oxidation—three processes 
usually involving liberation of heat. There is a net liberation or 
running-down of energy. Katamorphism is a great concentrating 
operation, with its maximum effect on igneous rocks, but also acting 
on sedimentary rocks so far as these contain minerals not already 
katamorphosed. 
Ores, whatever their ultimate origin, while insignificant in bulk 
as compared with the sediments, illustrate well the net results of 
repeated concentrations, physical and chemical, under katamorphism. 
Whether we start with the ores as original magmatic segregations, 
or with ores resulting from igneous “‘after-action,” or with ores 
derived directly from the katainorphism of igneous or sedimentary 
rocks, the ores become concentrated and segregated, and to a certain 
extent simplified, by katamorphism, and the richness and value of 
the metallic ore deposits are in a broad way proportional to the extent 
to which they have been katamorphosed. While some of the mag- 
matic segregations may have value without katamorphism, it is 
certain that their value is increased by katamorphism. When we 
consider the iron ores, the lead and zinc ores of the Mississippi Valley, 
and the oxidized and enriched sulphide zones of copper and other 
vein and replacement ores, the economic importance of katamorphism 
in the ore-depositing processes is obvious. A classification of ores in 
terms of metamorphism is a suitable one for instructional purposes, 
in that it emphasizes the correlation or identity of ore-depositing and 
