GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE VALLEY 91. 



interval unrepresented in this region by strata, The lower of 

 these breaks is a true unconformity as recognized in regions 

 of disturbed strata ; the upper may also be spoken of as an uncon- 

 formity, but in a limited sense. In cases to which the term is 

 most generally applied we have a discordance of dips between 

 the two series, indicating a period of folding and subsequent 

 erosion which precedes the deposition of the higher strata. The 

 z following diagrams indicate this kind of unconformity, to which 



Fig-. 2 A-F Development of a structural unconformity 



the term "structural unconformity " may be applied for pur- 

 poses of definition. Figure 2 a-d represents the condition from 

 the deposition of the first bed to the end of the deposition of 

 the second bed, and figure '2 e, f the results of another folding 

 and subsequent erosion. 



Unconformities of this type arc not show n in the Schoharie 

 region, bul they may be observed in the Rondout-Rosendale 

 region, southeast from Schoharie. Figures :\ a, b illustrate the 

 type of " stratigraphic or stratic unconformity" found in this 

 region between the Champlainic and Siluric formations as shown 

 in the table. 



