seam marks the line between a distinctly laminated stratum and one showing little lamination. This is best understood from a study of Fig. 23. Here the horizontal lamination of the upper stratum is distinctly continued into the downwardpenetrating columns. The laminae are sharply cut off at the edges of a column, but are continued in the next downwardpointing one. There is no evidence of distortion or disturbance of the lamination, either within the columns, or above them. At the ends of the upward-pointing columns, the laminae, instead of bending around the convex ends, retain

FIG. 23. Semi-diagrammatic sketch, showing the relation of stylolites to the lamination of the rock. Note that the distinct laminae of the upper layer are undisturbed, both above the upward-penetrating columns, and within the downward-pointing ones. The laminae are not bent around the ends of the columns, but are actually hollowed out. Note the darker laminae.

undisturbed their parallel, horizontal position, the rock having been actually hollowed out.

More striking yet is this observation of undisturbed lamination as seen where a stylolite-parting occurs between a cross-bedded and a horizontally bedded stratum. The most distinct example was observed by the writer at a quarry of J. Hoadley and Sons Co., Stinesville district (see Fig. 24). Here the overlying bed is distinctly cross-bedded, and the lower one clearly horizontally laminated. Very pronounced is the continuation of the angular lamination from the upper

FIG. 24.-Semi-diagrammatic sketch of a stylolite-seam occurring at the junction of a cross-bedded Note that the angular lamination of the above layer stratum and a horizontally laminated one.

is continued into the downward-pointing columns, and the horizontal lamination of the lower stratum is continued into the upward-pointing penetrations. Note, also, the presence of smaller intertoothed columns at the ends of the large, major penetrations. One-fourth natural size. quarry of J. Hoadley and Sons, Stinesville district, Monroe County, Ind.

stratum into the downward-pointing penetrations, and the presence of horizontal lamination in the adjacent, upwardprojecting columns.

Often dark laminae stand out very clearly in the stratification. Where penetrated by stylolites, they are missing (see Figs. 23 and 24). Under the pressure theory one should expect to find them displaced above or below the ends of the penetrating columns. Such is not the case. How could the various, above-described laminated conditions have been retained, had the sediments been "differentially compressed in a plastic state"? The rock materials have been actually re

FIG. 25.-Diagram of a small stylolite-seam partially eradicated by the penetration of upward-pointing columns of a large stylolite-seam. Mitchell limestone. One-third natural size.

moved, and the two beds have been "dovetailed" into each other.

Analogous to this observation of the removal of the laminae of the one bed into which the columns of the opposite have penetrated, are numerous examples of small styloliteseams which have been penetrated and removed by larger stylolites. Figure 25 is a case where a small, once-continuous stylolitic suture, following the lamination of the rock, occurs now only in the downward-projecting columns, being sharply cut off and absent in the rock of the upward-pointing parts. Under the pressure theory, should not one expect to find it displaced in the rock above the columns?

Since the solution theory requires an actual removal of rock material to an amount at least equal to the length of the stylolites-sometimes as much as a foot, which would mean that the rock strata had been reduced in thickness that amount-one might expect a sag of the overlying rock strata towards the center of the stylolite-parting, where solution reaches its maximum. The occurrence of such a sag is rare since stylolite-seams are so numerous and so distributed that the amount of displacement of one seam is compensated by that of an adjacent, underlying one. Such a phenomenon, however, was noticed by the writer, especially in one locality, a quarry of W. McMillan and Son, Reed Station district. Here, the occurrence of stylolite-seams is less common than usual. At the time of the writer's observation, a quarry face exposed an entire stylolite-seam, grading at both ends into a hardly noticeable line, and reaching a maximum thickness of eight inches in the middle. A sag in the seam and the welllaminated bed above it, equivalent to about eight inches (the maximum amount of penetration), was distinctly noticeable.

RELATION OF STYLOLITES TO THE COLOR OF THE ROCK. The difference in color of the Salem limestone presents some peculiarly interesting relationships in the study of stylolites. The sutures are frequently found at the contact of beds of the blue and buff varieties of stone, in which case the columns pointing in one direction will stand out in color contrast with. the adjacent ones (see Fig. 26). An interesting case is represented in Fig. 27 in which the blue and buff contact presents quite an irregular outline. Here, the irregular blue parts of the upward-pointing columns are not continued into the adjacent downward-penetrating buff columns. This phenomenon involves a consideration of the origin of the two colors of the stone. If the rock were all originally blue, according to the generally accepted theory, the question arises as to whether or not the irregular color change of the abovefigured example took place before, or after, the development of the stylolites. It would appear that the stylolitic development was subsequent to the color change-that the blue parts of the underlying stratum have been actually removed and are now occupied by the downward-projecting buff columns. of the overlying layer. If this was the case, the phenomenon furnishes additional evidence that the stylolitic structures

FIG. 26.-A typical, large stylolite-seam in the Salem limestone of the Dark Hollow district, Lawrence County, Ind. Note the irregularity in length and width of the interpenetrating parts. The darker, upper stratum is blue stone; and the lower, buff. Note the small, minor stylolite-seam running across the column below X. The clay parting is plainly visible. The upper and lower strata are distinctly lithologically different. The longest column is about 9 inches.