ELEMENTARY STUDIES OF SOME COMMON EOCKS. 287 



(1) A simple exercise is to ask the children to describe 

 the one or two samples placed before them. They will 

 note such points as the colour of the sand as a whole 

 the coarseness or fineness of the grains the degree of 

 rounding or angularity of the grains the number of 

 different ingredients the most abundant constituent 

 transparent grains and opaque grains the presence of 

 shells, spines of sea-urchins or organic constituents of any 

 kind whether any grains are attracted by a magnet 

 (magnetic iron-ore) whether the light or the dark grains 

 sink fastest in a test-tube with water whether acid affects 

 any grains the difference between the grains of sand and 

 of clay when rubbed on glass, and so on. 



All these points can be discussed though the teacher 

 knows nothing of the composition or characters of the 

 minerals that make sands. But for his own comfort of 

 mind it would be better that he should have an elementary 

 acquaintance with minerals. 



But too much of this type of exercise might become 

 tedious. The teacher should vary the work and interest 

 the children by referring to other aspects of sands. Two 

 illustrations will here suffice. 



(2) The drifting of sands, and the formation of dunes. 

 Eeference may b'e made to the destructive action of 



dunes, exemplified in so many places along our coasts, 

 where sand hillocks are gradually encroaching upon agri- 

 cultural lands and have even been known to bury villages 

 (Eccles, Norfolk). 



(3) A comparison of sand with sandstone. 



The child should be told, or led to find out for himself, 

 that sands and sandstones are essentially the same thing. 

 Crush a sandstone and you produce sand. Sandstones 

 are simply ancient beds of sand compacted into solid rock. 

 This opens out a wide field of inquiry about stratified 

 rocks and their history, into which the teacher may wander 

 as far as he dare. 



