PERMIAN. 497 



side of the uplift there is usually a bed of gypsum at a horizon about 150 feet above the base 

 of the formation, and east of Newcastle for some distance there is a 25-foot bed of gypsum at 

 the top of the formation, * * * several thin beds in its center, and at its base a local thin 

 bed of gypsum lying directly on the Minnekahta limestone. Throughout the Black Hills the 

 formation is distinctly separated from the underlying Minnekahta limestone by a very abrupt 

 change of material, and from the overlying marine Jurassic deposits by a well-marked erosional 

 unconformity. 



K 15. IOWA. 



Deposits of gypsum associated with red shale and sandstone which occur in 

 isolated areas in the vicinity of Fort Dodge, Iowa, have been assigned to the Per- 

 mian on the ground of lithologic relations, no fossils having been found. The 

 occurrences are described in detail by Wilder, ®^^ who considers also the alternative 

 possibilities of Triassic or Cretaceous age. 



L 20. NEW BRUNSWICK, NOVA SCOTIA, AND PBINCE EDWARD ISLAND. 



The Permian (in some of the reports called "Upper Carboniferous") of Nova 

 Scotia and New Brunswick was described by Dawson,^^" Logan, ^^^ and later by 

 Fletcher ^^*^-^^^ and Bailey.*^ In Fletcher's later report ^^^ he subdivides the 

 Permian as follows: 



1. New Glasgow conglomerate. 



2. Middle gray sandstone and shale group, with small coal seams. 



3. Upper red sandstone and shale group, with thin bands of limestone. 



These groups lie in parallel "belts along the shore of Northumberland Strait between Meri- 

 gomish and Wallace, dipping seaward, generally at a low angle, but broken by faults sometimes 

 of considerable magnitude. Between the second and third groups there is no distinct line of 

 demarcation and the subdivision is only one of convenience. 



The position of the New Glasgow conglomerate in relation to the productive 

 coal measures (Pennsylvanian) has been a matter of doubt, as it resembles the 

 "Millstone grit" at their base. Fletcher concludes that the "New Glasgow con- 

 glomerate is newer than the coal measures." He describes an unconformity 

 between the New Glasgow and the "Millstone grit." The dip of the former is not 

 so steep as that of the latter and " gray sandstone with greenish and reddish tints, 

 dipping 42° to 51°, is overlain by thick beds of very coarse conglomerate which 

 fills depressions in the lower beds." Again the conglomerate, though mostly com- 

 posed of material from the Devonian, contains large pebbles, some of which "are 

 certainly derived from the MiUstone grit or coal measures." This basal con- 

 glomerate of the Permian overlaps upon Devonian and Silurian rocks and varies 

 greatly in thickness, being in places perhaps entirely lacking or overlapped, yet 

 elsewhere apparently 1,300 feet or more thick. 



Sections of the higher Permian rocks, with a maximum total thickness of 8,000 

 feet, are given in much detail by Fletcher. 



Dawson, ^^^ who called these strata "Upper Carboniferous," did not recognize 

 the Permian in Acadia and devotes a brief chapter to the "Permian blank." His 

 description of the "Upper Carboniferous" is included in that of the Joggins 

 section ^^^ and of other coal fields of the region. 



48011°— 12— 32 



