98 BEACH GRASS 



structure with a covering thatch of grass and 

 weed stalks. This pale yellow covering has not 

 attracted the sun's rays but has protected the 

 underlying ice-infiltrated sand, while the sun 

 has melted the icy sand all about. The loose 

 sand is carried off by the wind leaving a small 

 tableland or butte of hard sand which is gen- 

 erally undercut to the mushroom shape. 



It is not always so easy to discover an explana- 

 tion for sand formations in freezing or thawing 

 weather. One of the most curious is one that 

 I have several times found at the end of a severe 

 winter in shallow pools of water in the dunes, 

 where mounds a foot or two across with rounded 

 and irregularly curved slopes appear to have 

 risen up above the water. The cracks in some of 

 them early in the season point to underlying 

 snow. They look like geological models. As 

 the water of the pools sink, these mounds appear 

 stranger still, surrounded as they are by ir- 

 regular ridges and grooves of sand, that look 

 as if a monster king-crab had been ploughing his 

 way through the wet sand. 



Later in the season some of the pools are 



