[whittaker] bottom DEPOSITS OF McKAY LAKE 147 



from adjacent laminae when these were only about a sixty-fourth inch 

 in thickness, so as to be certain that each sample was from one layer 

 only. This ooze was found to abound in rhizopods and diatoms but 

 no higher forms of life were found. The maximum depth at which 

 this red ooze was obtained is thirty-two feet, which is also the deepest 

 point on the lake bottom. 



Two other types of bottom deposit are present. At the extreme 

 south end of the lake for a distance of about one hundred feet the 

 shore consists of sand which has been derived from the sand beds 

 which border the lake on the south and east. The bottom for a 

 distance of one hundred feet from shore, which is there sand, is char- 

 acterized by a sparse assemblage of plant life, as well as by the absence 

 of many of the molluscs found elsewhere and by the presence of 

 Campeloma decisum. This species was found only at this point. 

 The eastern bay is floored by a mud-marl bottom which also produces 

 local differences in the flora and fauna which are more sparse here. 

 The map (see Figure 1) shows graphically the distribution as well as 

 other shore features. 



It is thus seen that in McKay Lake we have had a highly special- 

 ized type of sedimentation which owing to its small size can be studied 

 in detail. From large lakes its sedimentation processes are distin- 

 guished by: 



(1) Absence of pronounced wave action. 



(2) Absence of any lake currents. 



(3) Absence of large inflowing streams with their great burden 

 of sediments. 



(4). Absence of transporting agents, hence sediments where 

 derived from land are largely deposited near shore. Uni- 

 formity of meteorological conditions. This is impossible in 

 a large lake. 



(5). Large proportion of organic deposits. 



Field Studies 



As the red ooze-like material had not been hitherto encountered 

 it was felt that the acquisition of certain information with regard to 

 sedimentation in McKay Lake at the present time might throw some 

 light on its origin. A series of experiments were, therefore, conducted 

 with more or less success to find out whether sedimentation in the lake 

 was continuous or interrupted, and if the latter, its variation during 

 different seasons of the year. The actual work undertaken is indi- 

 cated below. Difficulties encountered were due mostly to the fact 



