Waves of sand and snow and the eddies which make them . andflow. In channels wholly submerged even at lowwater they produced ripples in the sand which weresimilar to the ripple-mark of oscillating sea-wavesin being symmetrical—, having equal slopes oneither side ; but they were not so steep, the lengthbeing twelve times as great as the height. Current-mark. The miniature sand-waves seen at the bottom ofclear streams have been called current-mark. I have made numerous observations of the sand-ripples in a little stream which flows across a sandybeach close to where I used to live on the Dor
Waves of sand and snow and the eddies which make them . andflow. In channels wholly submerged even at lowwater they produced ripples in the sand which weresimilar to the ripple-mark of oscillating sea-wavesin being symmetrical—, having equal slopes oneither side ; but they were not so steep, the lengthbeing twelve times as great as the height. Current-mark. The miniature sand-waves seen at the bottom ofclear streams have been called current-mark. I have made numerous observations of the sand-ripples in a little stream which flows across a sandybeach close to where I used to live on the Dorsetcoast, between Bournemouth and Poole Haven, andhave from time to time verified these observationsin other places. The stream issued from a culvert, and flowedat first at a speed of only 063 foot per second, witha depth nowhere greater than two-thirds of aninch. The surface of the water here was smoothand unrippled. The sandy bottom was irregular,having pools in places with little cliffs on their up-stream side one-third of an inch in height. The. S O O a. 263 RIPPLE-MARK AND CURRENT-MARK 265 distances from one cliff to another were irregular,and although there was some approach to trans-versality, yet in this respect, as in that of wave-length, they did not satisfy the ideal of ripples orwaves. Two opposing influences seemed to be atwork, one trying to make transverse, the otherlongitudinal cliffs. The surface of the sand wascompact and firm. In a deeper stream which makes its way throughthe sandy beach at Mundesley in Norfolk, thevelocity where it issues from its culvert was aboutthe same as in the last case, viz., o54 foot persecond, but the depth was greater, viz., 5 to 6inches. In this stream the cliffs were at intervalssufficiently regular to give the impression of ripplesor waves, and the average wave-length was 5*5inches. There was a position to leeward of thedeepest places from which I could see the sanddeparting in two directions, backwards towards thefoot of the
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