Stockdale: Stylolites 



29 



columns), in the direction of the pressure. If a cemented 

 portion, while being- compressed into the above soft mass, 

 should strike another partially consolidated part, then this 

 compression would be lessened, thus explaining the differing 

 lengths of stylolites of the same seam. 



4. Since it is possible to have pressure exerted in direc- 

 tions other than vertical, stylolites may also form in an 

 oblique, or even horizontal, direction. The clay and fossil 

 caps, however, seem to be lacking in these types of stylolites. 



Theoretically, Rothpletz's explanation sounds plausible. 

 However, field observations furnish an abundance of evidence 

 against it. This has been conclusively shown by Reis and 

 Wagner, and is discussed later in this paper. Were one to 

 accept his assumption that ''stylolites give no indications 

 pointing in any way to any essential chemical activity" his 

 theory would stand with less objection. His statement that 

 oblique and horizontal stylolites bear no clay caps is also at 

 fault. 



Solution Theory. The solution theory was first suggested 

 by Fuchs (1894, pp. 673-688). It was more thoroly estab- 

 lished by Reis, 1901-1902, and extensively reviewed and 

 studied by Wagner, in 1913. 



Investigations of Fuchs. After a careful study of stylo- 

 lites, Fuchs came to the conclusion that (1) they are formed 

 in hard rock by chemical solution, under pressure, along a 

 crack or crevice; the differential ability of the rock to resist 

 solution accounting for the interteething of the strata along 

 the line of solution ; (2) the clay cap is the non-soluble residue 

 of the dissolved rock substance; (3) the polished and striated 

 sides of the columns are a result of the movement which has 

 taken place. 



The first part of Fuchs' paper is devoted to a discussion 

 of the pressure theory and the experiment of Giimbel (see 

 p. 27) . The most important conclusions from Fuchs' investi- 

 gations may be summarized as follows : 



' 1. Stylolites never appear singly, but always occur col- 

 lectively, running in lines, forming the so-called ''Stylolithen- 

 bander". 



2. Contrary to the former assumption that stylolites de- 

 pend upon planes of stratification (all theories which were 

 formerly postulated proceeded from this supposition which 



