Stockdale: Stylolites 



51 



out that slight tremblings within the rock might cause fric- 

 tion, thus creating heat, which in turn would increase the dis- 

 solving powers of the solvents. The writer believes this lat- 

 ter conclusion to be unimportant in explaining the develop- 

 ment of such an intertoothed phenomenon as stylolites. 



From the solution theory it can be seen that a vast num- 

 ber of variations in size, shape, distribution, and character 

 of stylolites is to be expected, principally from (a) variations 

 in the composition and lithologic nature of the rock, (b) the 

 erratic distribution of varying soluble portions of the stone, 

 (c) variations in the direction of pressure exerted upon the 

 rock, and (d) the length of time solution has continued. 



The spacing of the alternating, less resistant portions of 

 the stone on the two sides of the crevice may occasionally be 

 quite regular. This, however, would be an exception. In 

 most cases the distribution would be very erratic, so that the 

 resulting columns would be of varying widths. In the be- 

 ginning, stylolite-seams are the small, finely serrated type. 

 A little further solution might, because of differential solu- 

 bility of the rock on opposite sides, develop a slightly undulat- 

 ing stylolite-seam, each of these undulations bearing smaller 

 penetrations in varying numbers. A continuation of the 

 process upon these compound major undulations might result 

 in the development of larger, major columns, whose ends 

 might be marked with the smaller, original penetrations, such 

 as are often observed (see Fig. 24), and still further con- 

 tinuation of solution might bring about a complete, or almost 

 complete, eradication of these original, smaller, intertoothed 

 parts. All sorts of gradations between the beginning, barely 

 noticeable, undulating line, and the large, major stylolite- 

 seams are to be observed in the field. 



If, in the gradual interpenetration of the stylolites, the less 

 resistant portion on the one side, which is being dissolved 

 out opposite the end of the column, changes in resistance so 

 that it is as resistant as, or more resistant than, the pene- 

 trating part, solution might then take place in the rock on 

 both sides, or change to the end of the column. Such vari- 

 ations in the chemical resistance to solution therefore often 

 produce quite a diversity in the length and shape of the inter- 

 penetrating parts (see Figs. 15 and 26). It explains the 

 occurrence of shorter stylolites between longer ones. If the 

 rock on each side of a solution crevice were of uniform re- 



