NORCROSS BEACHES IN MANITOBA. 393 



WESTERN NORCROSS SHORES IN MANITOBA. 



(PLATES XXX-XXXIll.) 



Throiigh towiislii]) 1, range .5, the Noreross shores of Lake Ag-assiz lie 

 on the escarpment of tlie Pembina Mountain, and the first observations of 

 tlieir beaches were in sections 7, 18, and 19, township 2, range 5, where the 

 mountain wall is reduced to a gradual ascent in the vicinity of Mountain 

 City and Thornhill. Aliout a half mile southeast of Mountain City the 

 upper Noreross beach is well displayed at John Borthwick's house, which is 

 built on its crest, 1,1G7 feet above the sea, in the southwest corner of section 

 19. Digging for wells here shows that the gravel and sand of the beach 

 extend only to a depth of G or 8 feet, there resting on the Fort Pierre shale. 

 From the crest of this beach ridge its slopes fall 8 or 10 feet within a few 

 rods on the east and about 4 feet on the west. It is bordered on the west 

 at this locality by a surface strewn with very abundant bowlders up to 5 

 feet or rarely more in diameter, nearly all being Archean granites, with 

 perhaps a third of 1 per cent of magnesian limestone. Generally, how- 

 ever, the surface in this vicinity has few or no bowlders; and a shallow 

 depth of ordinary till or of lacustrine deposits overlies the Cretaceous shale. 

 The second Noreross beach, also forming a distinct ridge, lies a third of a 

 mile farther east, with its crest about 1,150 feet above the sea. A large 

 excavation for sand to be used in plastering has been made in this ridge in 

 the south edge of this section 19. A mile farther south John W. Stodders's 

 house is built on it at an elevation of 1,148 feet. His well, 12 feet deep, 

 passes through gravel and sand, 11 feet, and then enters the slmle, the top 

 of which, to a depth of G to 12 inches, is a hard, calcareous layer, including 

 nodules and veins of calc spar. Pieces of the hard surface of this layer 

 thrown out of the well were plainly marked with glacial stria?. The con- 

 tinuation of these beaches is traceable through the next 7 miles northward 

 across the Southwestern Branch of the Canadian Pacific Railway, passing 

 about 3 miles east of Thornhill to Bradshaw's Creek, beyond which to near 

 Treherne they again coincide with the Pembina Mountain escarpment. 



About IJ miles east of the Little Boyne River, neai- Treherne, the 

 Manitoba and Southwestern Railway cuts the upper Noreross beach ridge, 



