REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1900 rl09 



line where the topographic conditioais were similar and the agen- 

 cies tended to make the shore feature® comparatively uniform. 



The horizontal measurements for the profiles were partly by 

 eye estimate and partly by pacing; this element, which is less 

 important^ is therefore only approximate. The vertical measure- 

 ments were usually by hand level, and sometimes repeated, and 

 the error in this important element is probably not much greater 

 than is the variation in the surface of each individual bar. 



Composition of the bars 

 The material or composition of the bars, whether coarse or fine, 

 was not always recorded, but it is usually either sand or finer 

 gravel, rarely coarse gravel. This factor may possibly be of crit- 

 ical importance, as indicating depth of water. However, the com- 

 position of the bars is thought to depend chiefly on other condi- 

 tions than depth, as the character, abundance and proximity of 

 the supply ; the exposure to the wind or the force of the waves; the 

 depth off shore; the strength of the shore currents. 



Vertical relation of the bars 

 The siginificanee of the bars with reference to changes of lake 

 level lies in the element of vertical relation. For purpose of 

 comparing the vertical spacing the chart of profiles (pi. 10) has 

 been prepared, and the tabulation p. 110. The figures in the 

 second column, for the highest bars^ are inexact only to the degree 

 of uncertainty in selecting a basal point on the lake bottomi plain, 

 which is not very difficult since this plain is quite definite. How- 

 ever, any error here does not in the least affect the figures in the 

 other columns. The figures of the third and fourth columns are 

 accurate, the only and rare uncertainty being the determination 

 of the highest bar. As shown by the map, the bars are not con- 

 tinuous, and therefore there is not absolute certainty of the iden- 

 tity or exact oorrespondence of the highest bars of the different 

 sections. However, considering the long stretches of continuous 

 beach, the large number of sections, and the long distance which 

 they cover, the practical identity of the upper level can properly 

 be assumed. 



