456 E. K. SOPER 



records. This valley also joins the main valley from the west, but 

 there is little evidence of its existence in the present surface topog- 

 raphy, which consists of low hills of drift and completely obliterates 

 any underlying channel. 



The pre-glacial river flowed almost due south from Lake Harriet, 

 but no attempt has been made to outline its exact course beyond the 

 city limits. In a general way this course can be traced for about 

 five miles south of Minneapolis through Grass Lake, Wood Lake, 

 and numerous small lakes and ponds to its junction with the Minne- 

 sota River valley somewhere east of the village of Bloomington. 



An important tributary valley had its confluence with the main 

 valley just south of Lake Harriet, at which point it entered from 

 the east. Evidence of this buried valley may be seen in the present 

 topography, especially along Minnehaha Creek, which follows the 

 course of the ancient channel, between Lake Harriet and Lake 

 Nokomis. At the latter point the old valley turns sharply to the 

 south. 



At Powderhorn Lake a small valley heads and flows southward 

 to Rice Lake where it joins the tributary just described. This 

 region around Powderhorn Lake is particularly interesting in this 

 connection, for it has usually been considered to be a large Kettle 

 hole. 



North of the mouth of Bassett's Creek the Mississippi River 

 flows over the same course that was formerly occupied in pre- 

 glacial time. The old channel has been almost filled with sediments 

 and drift so that the present stream bed, which consists of glacial 

 debris and recent clays and silts, lies in this region at an elevation 

 of at least i6o feet above the bottom of the buried vafley. At a 

 point about half way between the mouth of Bassett's Creek and 

 the north city limits, along the river between Twenty-sixth Avenue 

 North and Thirty-first Avenue North, a large tributary vafley 

 joined the pre-glacial river. This buried valley follows a course 

 indicated in the present topography by a low swampy zone extend- 

 ing northeastward from the river through Sandy Lake (now dry) 

 across Columbia Park, and beyond the city to Silver Lake. The 

 exact course of the vafley north of Silver Lake has not been deter- 

 mined. 



