156 W. A. Bell — Mississippian Formations of 



by H. S. "Williams the Acadian orogeny. Although this 

 disturbance must have resulted in a constructional topog- 

 raphy of high relief, the basal Mississippian contact in 

 the Windsor district indicates that these mountains were 

 worn down to peneplanation prior to early Mississippian 

 times. Not only do the basal Horton sediments of Kin- 

 derhookian age truncate at a flat angle both slates and 

 granite, but there is evidence of pre-Mississippian weath- 

 ering in the oxidized nature of the slates and in the dis- 

 integrated condition of the granite for several feet be- 

 neath the contact. 



Structure and physiography. — The slopes that connect 

 the lowland with the upland are everywhere steep. In 

 the western margin of the district there is a rise of sev- 

 eral hundred feet within half a mile, while the ascent in 

 the south is still more abrupt. The latter was determined 

 to be the erosional expression of a fault, here named the 

 Butler Hill fault, that has a stratigraphic throw in the 

 district in the neighborhood of 2,000 feet. As a result, 

 hard crystalline rocks on the south are brought up against 

 very soft rocks of the W^indsor series of upper Mississip- 

 pian age. This fault that margins the Windsor lowland 

 in the south was traced for several miles northeastwards 

 beyond the confines of the district. The border of upland 

 and lowland in the west does not show a response to fault- 

 ing, but is a sinuous one determined by post-Mississippian 

 folding that has affected the crystalline floor as well. 

 The present main streams, e. g., Gaspereau river. Half- 

 way river. Mill branch and W^est branch, all of which are 

 tributaries of the Avon river, are located in synclinal val- 

 leys that are underlain by Mississippian rocks, whilst the 

 divides between these streams are in the nature of pro- 

 jecting ^^ capes'' from the upland developed on the older 

 crystalline rocks. This relation has given rise to the 

 erroneous impression current in the literature that the 

 margin of lowland and upland is an inheritance from an 

 old Carboniferous shore-line. 



The lowland of the Windsor district is underlain by 

 rocks of so soft a nature and is so maturely dissected by 

 the Avon river and its tributaries that it is not known to 

 what extent its formation is due to marine planation on 

 the one hand or to subaerial denudation on the other. At 

 present, the lower reaches of the rivers are submerged 

 and an estuarine cycle is in process. Tides of 20-30 feet 

 mean range have resulted, and that these are eifective 



