68 STEPHEN TABER 
limestone were adjusted by recrystallization, in the same way that 
slabs of marble or limestone may be slowly deformed under forces 
acting through a long period of time. This process probably also 
explains the curving walls of the lenticular veins. 
The facts here listed are difficult or impossible of explanation 
under any of the hitherto generally accepted theories of vein forma- 
tion. They are, however, easily explained on the hypothesis that 
Fic. 4.—Calcite veins in limestone showing inclusions of the wall rock. Two- 
thirds natural size. 
the vein-forming solutions entered along fractures, bedding planes, 
or other planes of weakness, where the openings were chiefly capil- 
lary or subcapillary in size; and that the separation of the vein 
minerals from solution was accompanied by the development of a 
force sufficient in magnitude to push apart the walls, and thus 
gradually make room for the growing veins. Circulation of solu- 
tion through such narrow openings must necessarily be extremely 
slow, and under these conditions diffusion through the solution 
becomes an important factor in supplying additional material to 
the growing crystals. 
