84 EXPEDITION TO THE 



On reaching the outlet of Winnepeek river, wc observed a 

 great change in the aspect of the water, which was clear and 

 transparent ; this was soon accounted for by meeting with 

 sienitic rocks in place, and we were informed by our guides 

 that similar rocks extend all the way up the river. About 

 a mile beyond this we reached Fort Alexander. The junc- 

 tion of the primitive and secondary rocks is therefore about 

 50° 45' of north latitude and about 96° 30' of west longi- 

 tude. It appears probable, from all the information which 

 we have collected, that the whole of the eastern shore of 

 Lake Winnepeek, is occupied by a primitive formation, 

 Avhilc the western is composed of secondary, and these pro- 

 bably limestone, rocks. This accounts for the fact that the 

 prairies are limited to the east by that lake, while they ex- 

 tend as far north as the Saskatchawan and to a considera- 

 ble distance up that stream. It appears to us by no means 

 improbable that the excavation of this lake was occasioned 

 by the easier decomposition of the strata at the junction of 

 the two formations. No where, perhaps, upon the surface of 

 the earth, is a difference in the geological characters of the 

 country attended by a more striking diversity in the su- 

 perficial or topographical aspect. We observe here, that 

 Avherever the primitive rocks prevail, the country abounds 

 in lakes, swamps, short streams filled with falls and rapids, 

 as is the case with the whole country which extends from 

 Lake Winnepeek to Lake Superioi', and which reaches 

 nearly to the Falls of St. Anthony on the Mississippi, 

 while the secondary formation is covered with fine high 

 ?ind dry prairies. The track which our party followed must 

 have been very near to the eastern limit of the secondary 

 or prairie country, as all the eastern tributaries of Red ri- 

 ver or the St. Peter, are represented as rising in those 

 small lakes and lagoons. It would be curious to ascertain 



