6 
MUSEUM BULLETIN NO. 21. 
pear for more than 50 miles below Pas, At the Cedar Lake 
mouth of the river, however, numerous low cliffs of limestone 
are exposed along the banks of the river and along the sides of 
the islands at its mouth. The south shore of Cedar lake is low 
and swampy until the east end is approached; where numerous 
small rocky islands and ledges of limestone occur. These 
limestone ledges outcrop at frequent intervals and give rise to 
four rapids above Grand rapids. Between the Roche Rouge 
and Grand rapids the river flows for a short distance between 
high banks of glacial till before cutting across the scarp of Silurian 
rocks near its mouth. 
The outcrops examined in the Saskatchewan valley thus 
fall into four groups if areally considered. The most westerly 
of these is exposed in the cuts of the Hudson Bay railway from 
4 to 25 miles northeast of Pas. The other three lie respectively 
in the Cedar Lake estuary of the river, about the eastern shore 
of Cedar lake, and along the lower part of the river between 
Cross lake and the foot of Grand rapids. 
STRATIGRAPHY AND FAUNAS. 
The rock exposures at Grand rapids afford the best section 
of the Silurian which is known in Manitoba. Near the head of 
the rapids at the narrowest part of the channel the River cliffs 
of Silurian dolomite rise about 30 feet high on either side of 
the river. Beds somewhat lower than the base of these cliffs 
are exposed a short distance above the head of the old overflow 
or cut-off channel. Beds about 40 feet higher than the top of the 
River cliffs are exposed near the old tramway. A section com- 
bining the beds exposed in the lower and upper part of the 
Rapids together with those near the tramway is shown following. 
