10 
MUSEUM BULLETIN NO. 21. 
the opposite shore. West of Derai-charge rapids, the dolomite 
is well exposed along the south shore of the broad expansion of 
the river. These rise 35 to 40 feet above the river in places. 
Small caves are seen at some points opening a little above the 
water. Sink holes of rather small size connect with some of 
these. Fossils are rather scarce in these dolomites. A consid- 
erable collection made on a bluff 2 miles west of Demi-charge 
rapids, together with others from the eastern shore of Cedar 
lake, was lost in a canoe accident. Low cliffs of light grey dolo- 
mite 5 to 25 feet high in horizontal beds occur at frequent inter- 
vals along the southeast shore of Cedar lake as far west as 
Collins island. The most westerly of these exposures is located 
about 5 miles southwest of Collins island. None of the many 
exposures observed about the east end of Cedar lake suggest 
any deviation from horizontality to the eye, but it is probable 
that a gentle southwesterly dip of a few feet to the mile prevails 
throughout the district. If this inference, which is based on the 
demonstrated higher position stratigraphically of successive 
exposures of the limestones about the northern shores of Lake 
Winnipegosis, is correct, the dolomites in the vicinity of Collins 
island are higher in the section than the topmost beds of the 
Grand Rapids section. 
Along the south side of Cedar lake, west of Collins island, 
the shore for 20 miles or more is very low and no outcrops of bed- 
rock were observed. Occasional loose slabs were seen along this 
shore with an abundance of Stropheodonta acanthopteria. It 
appears probable that the horizon of the Gypsumville gypsum 
lies near the surface along some parts of this low-lying south 
shore to the west of Collins island. 
At the western end of Cedar lake the Silurian dolomite 
outcrops in some of the small islands which lie not far off the 
mouth of the Saskatchewan river. Other good exposures of the 
rock occur in a low bluff about 6 or 8 feet high near Chemahawin, 
the Hudson’s Bay Company’s post near the mouth of the river. 
A collection of fossils was made from a rocky point about 2 miles 
west of Chemahawin. About 5 feet of flat-lying, hard, buff- 
coloured dolomite at this locality afforded the following species: 
