334 



THE NATURE BOOK 



rhotOi:raph l'\ 



'LIMESTONE USUALLY WEATHERS INTO BROAD UPLANDS 

 The edge of the moors from Lastingham. 



world they give rise to the phenomena 

 of volcanoes. We meet with many 

 igneous rocks 

 in our islands 

 which prove 

 that our coun- 

 try has been the 

 scene of vigor- 

 ous volcanic ac- 

 tivity at many 

 times and in 

 many places. 



We cannot, 

 at the present 

 day, trace in 

 our mountain 

 topography the 

 outlines of vol- 

 canic cones, the 

 craters, lava 

 streams and 

 ashes, such as 

 are to be seen 

 in Vesuvius, the 

 Auvergne, and 

 other regions 

 where vulcan- 

 ism is still at 

 work or only 



just extinct. 

 Our \'olcanoes 

 have been so 

 dissected and 

 worn down that 

 only fragments 

 remain, but 

 they are often 

 sufficient to re- 

 construct i n 

 large measure 

 the events 

 which took 

 place when 

 they were ac- 

 t i V e. Antrim 

 and the Inner 

 Hebrides are in 

 great measure 

 built up of 

 great flows of 

 lava piled 

 above each 

 other in places 

 to a height of 

 over two thou- 

 sand feet. 

 In the Lake District and in North 

 Wales we have a great development of 



jm 



"WE ARE Ni 



I \i'l, ^^\' THUR l':XISTI-;NCi'. I NTIL WE STAND ON THE 



VERY BRINK OF THEIR FRKCIPITOUS SLOPES." 

 The escarpment of Efilwyscg Rocks, Llangollen. 



