STYLOLITIC STRUCTURE IN TENNESSEE MARBLE 565 
nation was accepted in 1838 by Vanuxem and the name ‘“‘epsomites”? 
applied to the structure in the belief that it represented the crystal- 
lization of sulphate of magnesia. Among others who accepted the 
mineral theory with modifications were James Hall, Ebenezer 
Emmons, and T. Sterry Hunt, the last named proposing for them 
the name “‘crystallites.”’ 
Pressure theory.—The first to suggest that this structure is due 
to differential compression of sediments before consolidation was 
Quenstedt,* followed soon after by Marsh.2 Experimental demon- 
stration of the theory was attempted by Gumbel,’ but as Wagner 
points out the results were not convincing. 
Following Marsh’s explanation it is assumed that a thick bed 
of carbonate of lime is deposited as a fine soft ooze over the surface 
of which are scattered the remains of organisms, such as shells, etc. 
This is then covered by a very thin layer of argillaceous mud, upon 
which is deposited more calcareous matetial, whose increasing weight 
tends to condense the mass below. As a result of the resistance 
offered by the shell or other organic substance ‘‘the surrounding 
material will be carried down more rapidly, thus leaving columns 
projecting above, each protected by its covering and taking its 
exact shape from its outline.” According to this theory, therefore, 
the structure is due to differences in the amount of compression in 
the material beneath and around the shell before consolidation as 
a result of the weight of the overlying mass. The fact that the 
columns are not always capped by shells (in Tennessee marble 
rarely), and, further, as pointed out by Grabau,‘ that there is no 
evidence of deformation, or crowding or squeezing around or above 
the columns, is against the theory of simple compression either before 
or after consolidation. Moreover, the fact that the sutures are 
often oblique or even at right angles to the plane of sedimenta- 
tion is clearly opposed to this theory. The occurrence of such 
1A. Quenstedt, Epochen der Natur, 1861, pp. 200, 489. 
70. C. Marsh, Proceedings of the American Association for the Advancement of 
Science, XVI (1867), 135-43. 
3 Gumbel, Zeitschr. Deutsch. geol. Ges., 1882, p. 642; ibid., 1888, p. 187. 
4A. W. Grabau, Principles of Stratigraphy, 1913, p. 787. 
