CHAPTER VIII 

 QUICKSANDS AND FIRE-STONES 



THERE are curious facts about sand which can be 

 studied on the seashore. There are the " quick- 

 sands," mixtures of sand and water, which sometimes 

 engulf pedestrians and horsemen at low tide, not only 

 at the Mont St. Michel, on the Normandy coast, but at 

 many spots on the English, Welsh, and Scotch coasts. 

 Small and harmless quicksands are often formed where 

 the sand is not firmly " bedded " by the receding sea, 

 and the sea-water does not drain off, but forms a sort of 

 sand-bog. Then one may also study the polishing and 

 eroding effect of dry blown sand, which gives a " sand- 

 glaze" to flints, and in "sand-deserts" often wears away 

 great rocks. The natural polishing of flints and other 

 hard bodies by fine sand carried over them for months 

 and years in succession by a stream of water, is also a 

 matter of great interest, about which archaeologists want 

 further information. 



A very interesting fact about the ordinary sand of 



the seashore is that two pints of dry sand and half a pint 



of water when mixed do not make two pints and a half, 



but less than that quantity. If you fill a child's pail with 



dry sand from above the tide-mark, and then pour on to 



it some water, the mass of sand actually shrinks. The 



reason is that when the sand is dry there is air between 



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