158 W. A. Bell — Mississippian Formations of 



The basal Mississippian sediments belonging to the 

 Horton formation that flank the upland in the west have 

 suffered practically no folding beyond the broad flexures 

 already noted. To the northeast, however, where higher 

 and better laminated strata of the Horton outcrop along 

 Minas basin, they are affected by numerous minor asym- 

 metrical folds and corrugations which have their axial 

 planes inclined to the northwest. 



The very soft strata of the Windsor series are charac- 

 terized by numerous small flexures and are broken by 

 many faults that are mainly thrust slips consequent upon 

 stretching of the limbs of the folds. In general, these slip 

 planes dip steeply southwards, and where closely spaced, 

 the strata have isoclinal dips and are locally overturned. 

 Such a complex structure, combined with the presence of 

 thick zones of gypsum and very poor exposures, renders 

 the interpretation of the stratigraphic sequence exceed- 

 ingly difficult. The stratigraphic throws along the slips 

 vary from several tens to several hundreds of feet. 



The northward dip of the axial planes of the folds in the 

 northern part of the district is believed to be due to the in- 

 fluence of the resistant crystalline mass of the Cobequids 

 north of Minas basin, which bulwark is expressed topo- 

 graphically at the present time by the narrow upland 

 known as the Cobequid mountains. 



Post-Mississippian history. — The Windsor series of 

 late Mississippian age is the last sedimentary record of 

 marine transgression within the Maritime Provinces 

 prior to the Champlain epoch. The folding that affected 

 the Mississippian rocks took place before the close of mid- 

 Pennsylvanian (Westphalian) time, with the balance of 

 evidence in favor of an early Westphalian orogeny. 

 Eocks of Pennsylvanian age have been entirely removed 

 by erosion from this district, with the exception of a very 

 small patch of sandstone that may represent a faulted 

 inlier. The district was once more reduced to peneplana- 

 tion before the deposition of the semi-arid terrestrial de- 

 posits of Newark age (early upper Triassic). 



Stratigraphy and Correlation. 



Mississippian sequence, — ^In descending order the suc- 

 cession of Mississippian formations is as follows : 



