lower end of the lake outflow to the St. 

 Clair River appeared to consist of a mean- 

 dering surface current, near or east of the 

 midline of the lake, which approached the 

 entrance of the river from the northeast." 



Drift-bottle movements in 1956 



In the present investigations, only 

 one bottle was found below the head of the 

 St. Clair River that flows out of Lake 

 Huron. Of the many bottles that rounded 

 the Michigan Thumb, most landed on the east- 

 ern side of the Thumb before reaching the 

 river mouth. These recoveries lend some 

 support to Ayers' contention that outflow 

 to the St. Clair River was from the north- 

 east. 



Recoveries of 416 bottles from 760 

 releases along 3 transects in the southern 

 part of the lake (fig. 4) are considered in 



the analysis of Lake Huron water movements. 

 A striking feature of the returns from 

 these releases was the scarcity of recover- 

 ies from the Saginaw Bay area (fig. 14). 

 Only 16 bottles were found within the bay 

 and none of these had penetrated more than 

 10 miles. Penetration into the bay was 

 correlated with easterly winds during the 

 time the bottles were adrift. As Harrington 

 (1895) and Ayers e_t al. (1956) have indi- 

 cated, however, a strong current may at 

 times pass down the west shore of Lake Huron 

 and set up counterclockwise rotation at the 

 mouth of Saginaw Bay. Had bottles been 

 released near the west shore above Au Sable 

 Point, it is possible that many would have 

 been carried into the bay by such a current. 



The remainder of the recoveries from 

 the Lake Huron shores were scattered widely. 

 The tendency was marked, however, for the 

 bottles to drift to the east (fig. 15). 

 All recoveries from stations 2-8 were from 

 the Michigan Thumb area, mostly on the 

 ..northern and Ccistern sides and from the 



STATUTE MILES 



Figure 14. — Location of 16 drift-bottle re- 

 coveries in Saginaw Bay from 760 releases 

 on Lake Huron. Eighty bottles were re- 

 leased each at stations 1-6 and 40 each at 

 stations 7-13. X's mark recovery points. 



Figure 15. — Location of 45 recoveries from 

 80 drift-bottle releases at a Lake Huron 

 station. Triangle marks release point; 

 X's mark recovery points. 



17 



