RECENT AND FOSSIL RIPPLE-MARK. 
31 
the generally sandy shores along parts of its course above lake 
St, Peter afford favourable conditions for the formation of ripple- 
mark by wave action, in the very shallow water along shore 
where the current alone is not strong enough to produce ripple- 
mark, Where the current is strong in the deeper water of the 
river, true current ripples unaffected by wave action are doubtless 
formed where the bottom is suitable but these were not observed. 
We are at present concerned only with ripple-mark developed 
along the shore by waves produced by the wind. These are 
generally parallel with the shore. In one case symmetrical 
wave ripple-marks were observed within 4 feet of ripple-marks 
which though due primarily to wave action had been given an 
asymmetric form by the very gentle current which reached them. 
Examples of the two types within a few feet of each other were 
marked and the symmetrical ripple-mark was found to be 
stationary while the asymmetrical forms a few feet away moved 
\\ inches in 25 minutes. At a point above Lanoraie, Que., on the 
west bank of the St. Lawrence, the following notes were made 
on the wave-made ripple-marks observed: A strong upstream 
breeze makes waves out in deep water transverse to the channel ; 
but along the beach waves come in parallel to the beach with 
crests 6 to 10 inches high and 4 to 8 feet apart. These have kept 
the bottom rippled in the shallowest water (1 to 5 inches) with 
asymmetrical ripples with crests about 1| to \\ inches apart. 
Three of these were marked and observed. Their crests moved 
shorewards a distance equal to their amplitude (crest to crest 
If inches) in 20 minutes. Water was 3 inches deep. Above 
observations were repeated in 6 inches of water where crests are 
2 inches apart; ripples moved shorewards at the same rate, viz., 
distance of amplitude, 2 inches, in 20 minutes. 
Comparison of the profile (Figure 4 G) of the moulds of modi- 
fied wave ripple-mark taken at Lanoraie with typical current 
ripple-mark profiles from Windsor (Figure 3 C and D) shows a 
marked difference in the degree of asymmetry, the latter showing 
a very much steeper lee slope than the former. There is con- 
siderable difference in this respect also among the current 
modified ripples, some specimens like Figure 4 G showing a barely 
perceptible amount of asymmetry. 
