1912] 



Louderback : Pseudostratification 



31 



with considerable dip. Some of these planes appeared as if they 

 had been formed by a bodily slipping of the wet, poorly cemented 

 sand material, and the consequent development of a plane of 

 more easy water percolation, and therefore silica deposition. 

 Such slipping - surfaces may be plane for several meters, or they 

 may be short, irregular, or curved and give the appearance of 

 cross or current-bedding. 



Some of the lamellae show a visible banding of the fer- 

 ruginous cement parallel to the bounding surfaces. This may 

 in part antedate the formation of the layers, and may have 

 contributed to their production, but in several cases carefully 

 examined, the distribution of ferruginous bands was so peculiarly 

 related to the form of the layer, that it seems necessary to believe 

 that they were later and dependent on it for their form of 

 deposition. 



Transmitted March 4, 1912. 



