THE METAMORPHIC CYCLE 311 
igneous and crystalline rocks, constructive to sedimentary rocks 
made up of end-products of katamorphism. It is true that the 
katamorphism of an igneous rock is most rapid and effective at the 
surface, while the cementation of the sediments occurs best at and 
immediately below ground-water level, and anamorphism of sedi- 
ments begins only when the zone of rock-flowage has been reached. 
Thus there is a vertical succession of metamorphic zones, each with 
its own distinguishing characteristics; but in each of these are 
ec iS el 
Pri iS a 
Tgneous (aa SE a 
Rocks Limestone Sandstone Shale 
pe i dS Nata ase ras a tH os Toe 
A \ 
/ 
Belt of } \ 
Weathering / \ 
G¥arnkise) Oestructive \ 
! 
! 
Belt of 
Gementatian 
( Van Hise ) 
I 
i 
! 
' 
| 
i 
\ 
Zone of 
Anamorphism Pa 
(Van Hise) Fusion necessary s 
ta complerve Cycle ee “e 
Fic. 2.—Sketch to show principal changes of principal rock in relation to zones 
of metamorphism. Thickened line indicates locus of maximum change. Horizontal 
lines indicating boundaries of zones are not corrected for thickness of zones or varying 
depth of zones for different rocks. 
subordinate changes on opposite sides of the cycle. Katamorphism 
of an igneous rock near the surface is important, while, in the same 
zone, there is a minor amount of cementation of sedimentary rock. 
Cementation of sedimentary rock is important below ground-water 
level, where an igneous rock undergoes a relatively small amount of 
katamorphism. Anamorphism of certain sediments, especially 
