66o 



PRINCIPLES OF STRATIGRAPHY 



marine surface must be piled up to some extent in the deeper areas 

 where it comes to rest. As the result of such gliding the strata must 

 suffer much deformation, especially if they are at all consolidated. 

 Such deformations have all the characters of orogenic disturbances 

 due to lateral pressure, and indeed it has been suggested that some 

 extensive mountain folds and overthrusts may have originated in 

 this manner. These deformations will be more fully discussed in 

 Chapter XX. 



Accessory Features of Subaqueous Gliding. Among the ac- 

 cessory features produced by subaqueous and especially submarine 

 solifluctions, we may mention in addition to the deformations al- 

 ready noted, and to be more fully discussed in a later chapter, the 

 following phenomena : 



\ 2 



Fig. 131. Diagram illustrating the changes in stratification due to subaquatic 

 gliding. In the shore section strata are eliminated, while farther 

 out duplication occurs. (After Heim.) 



I. Increase of the strata in the lower regions where the shore 

 material is carried by gliding, and where strata are thus repeated by 

 the superposition of portions of the same strata upon one another. 

 2. Reduction of the number of strata in the zone affected by the 

 gliding where the ends of the strata are thus removed, and on the 

 deposition of subsequent beds a local disconformable relation is pro- 

 duced with hiatus signifying no appreciable time interval. 3. Su- 

 perposition of older on younger beds. Thus at Zug, the mass which 

 slid into the sea was more than 99 per cent, formed during the 

 former high-water period of the lake, and came to rest by gliding 

 upon the deposits formed since the present water level was estab- 

 lished (Fig. 131). 4. Displacement of facies. Thus at Zug gravel 

 and even coarse blocks were carried by gliding into the region where 

 they would otherwise be absent. In submarine solifluction shore 

 sediments may be carried out to the neritic belt, or the latter into 

 abyssal regions. A shore breccia may thus come to lie among off- 

 shore marine sediments. 5. Destruction of life. The benthonic and to 



