502 CHARLES A. DAVIS 



The pebbles mentioned above as occurring on parts of the 

 shore are also the result of the development and growth of an alga, 

 Zonotrichia or a nearly related genus, a much lower type than 

 Chara, having a filamentous form. The vegetable origin of these 

 pebbles would not be suspected until one recently taken from 

 the water is broken open, when it is found to show a radiating 

 structure of bluish-green lines, the color indicating the presence 

 of the plants, as it is characteristic of the group to which Zono- 

 trichia belongs. 



The relation of the deposits about Littlefield Lake to the 

 direction of the prevailing strong winds of the region is prob- 

 ably significant. 



The area of deposition is at the southeast end and along the 

 whole western side of the lake. The winds which would be most 

 effective in the valley of the lake would be those from the north 

 and northwest, which would drive the surface waters down the 

 lake toward the southern end, and, striking the shore on the 

 eastern side, these currents would be turned across the lake lo 

 the west, depositing sediment at the turning area and in slack 

 water beyond. The daughter-lakes are not easily accounted for 

 except in a general sense, that they were formerly deep bays, 

 which, by the building out of points of marl on either side of 

 their mouths, were finally enclosed. The tendency, already 

 noted, for existing bays to have points of marl of spitlike form 

 extend from either side of the mouth would seem to indicate 

 this as a probable method of formation. On the island at the 

 south end of the lake there was manifestly a strong current, which 

 was running southeasterly and depositing fine marl on the east 

 side of the island, the wind, at the time the observation was made, 

 blowing gently from a few points north of west. 



As has been already noted, the islands consist of marl from 

 twenty-five to thirty feet deep, the bottom on which they are 

 built up being, to judge from soundings made with an iron rod, 

 of rather fine sand. These foundations of sand have deeper 

 water all around them, if soundings said to have been made by 

 local fishermen can be relied upon ; so it is possible they 



