Effects of tbe (Blacfal fceriofc. 237 



the story to the present and future ages. 

 Much of the history of those times is a sealed 

 book, but the persevering energy of the gla- 

 cialist and archaeologist is gradually turning 

 the leaves of this old book and revealing new 

 chapters of the wonderful story of the ice. 



As the ice receded the arctic zone again 

 traveled northward, and many animals, plants, 

 and trees that had survived the vicissitudes of 

 the ice age, traveled back with it. Some of 

 them, however, became acclimated and by 

 adapting themselves to the new conditions re- 

 mained behind to live and grow with the 

 aborigines of preglacial times. Some of the 

 plants and flowers that grew in profusion im- 

 mediately under the edge of the great ice sheet 

 were unable to live under the new conditions 

 of increased warmth that came with the 

 retrograde movement of the ice and either 

 had to follow closely the receding ice or escape 

 to higher altitudes, where they found a con- 

 genial clime. Thus it is that we have arctic 

 plants and flowers above the timber line and 

 near the snow line of our high mountains. In 

 proof of this theory it has been found that 

 these arctic plants do not exist upon high 

 mountains, such as the Peak of Teneriffe, 

 where they have been isolated from the gla- 

 ciated region. The Peak of Teneriffe is situ- 

 ated on one of the Canary Islands, surrounded 

 by water, so that there was no possible chance 



