46 THE BOOK OF NATURE STUDY 



heat of the valley, and begins to melt away, leaving only a great 

 turbid river, which can be compared to the muddy streams that 

 we see trickling away from the snow drifts when the thaw comes. 

 In Britain, in those old days, all the low ground was deadly cold 

 too. There was nothing then to melt the ice, which pushed its 

 way downwards to the sea. Those great ice streams probably 

 pushed their way right out into the sea, just as the great ice 

 masses in the Antarctic now push their way out into the sea; 

 just as in the Antarctic at present they probably ended in great 

 Ice Barriers, huge walls of ice, from which enormous flat-topped 

 icebergs separated off and floated away. 



In the north at the present time the ice behaves a little differ- 

 ently. Here we have smaller tongues of ice, true glaciers, which 

 push their way towards the sea, and as they enter it irregular 

 masses break off, the icebergs of the north, which float away 

 southwards with the currents. 



Some such picture as this we might present, just suggesting 

 at the same time the different ways in which we recognise the 

 old work of ice in the existing features of our country. 



Many other observations on ice and the work of frost may 

 also be made, for it should be remembered that while on the 

 one hand it is difficult to make the conditions existing at other 

 parts of the earth's surface real to the child unless attention 

 has been deliberately drawn to the home conditions, on the 

 other hand it is equally true that once the imagination has been 

 stimulated by interesting accounts of different conditions, the 

 home conditions will be studied with renewed zest. We have 

 spoken, then, of the huge flat-topped icebergs which break off 

 from the great Ice Barrier in the Antarctic Ocean, we have spoken 

 also of the smaller, more irregular forms found in the north. We 

 have shown for what great distances these ice-masses may float 

 before they are finally conquered by the warm water as they 

 reach the hotter parts of the ocean. The ice on the rain-water 

 barrel or in the pond may next be used to make mimic icebergs, 

 to answer the question why icebergs float. We have reconstructed 

 in imagination the playground with its little heaps of snow as 

 Greenland or as Britain in the Ice Age. We have imagined 

 that from those snow heaps glaciers were slowly creeping out, 



