924 



THE NATURE BOOK 



HERE NATURE HAS USED RAIN AND LAND-SPRINGS 

 AS HER TOOLS. 



pageant of endless form and colour, we 

 are enthralled with the quiet beauty of 

 the scene spread out before us. When 

 at last we turn reluctantly away to con- 

 tinue our tramp across country, we 

 carry with us a mental picture of the 

 charm of that wild landscape which will 

 return to us again and again through 

 the years to come. These gently swelling 

 lava plateaux over which we tramp are 

 relics of volcanic activity which took 

 place in a past geological age, called the 

 Tertiary Period. 



If we explore the cliffs towards the 

 Giant's Causeway, we shall be able to 

 trace the double structure of these ancient 

 lava streams. On the storm-swept face 

 of these cliffs of black-brown, volcanic 

 rock, almost every alternate layer shows 

 in the form of graceful six-sided basaltic 

 columns. The layer above each zone of 

 these columns represents the upper and 

 more irregular portion of the ancient lava 

 stream, while here and there we shall see 

 some massive flows which have escaped 



columnar division entirely. The Giant's 

 Causeway is really the basal part of one 

 of these lava streams, which we have 

 seen in its entirety in the terraces of the 

 cliff close by. As we look down upon the 

 most worn portion of the Causeway, the 

 surface presents the appearance of a 

 titanic tessellated pavement, and we can 

 easily understand how this wonderful 

 example of Nature's masonry came by its 

 name. 



One cannot gaze upon those beautiful 

 symmetrical columns, so uniform in shape, 

 without marvelling at the forces which 

 moulded them in the dim past of the 

 Tertiary Period. Volcanic energy, great 

 heat, and chilling air are the tools with 

 which Nature has shaped these six-sided 

 columns out of the lava streams ; and 

 wherever volcanic eruptions are taking 

 place to-day, there these columns are 

 being formed, just in the same way 

 as those of the Giant's Causeway were 

 formed in the lava flows of the Tertiary 

 Period. F. Martin Duncan. 



