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The Garden Magazine, October, 1919 



in the climate of the Northern Hemisphere. Geologists are 

 pretty well agreed that the two great oceans, Atlantic and 

 Pacific, have not changed much in the aeons of time since 

 this earth began to cool. Seas, plains and mountain ranges 

 and areas of land have, however, changed vastly, though 

 probably the depressions and elevations have maintained 

 a fairly stable equilibrium — a sort of compensating bal- 

 ance. 



THE Tertiary period — the geologic era immediately 

 preceding the present — was one of great disturbances; 

 the folding of the Earth's crust, due to internal cooling and 

 consequent contraction, made vast changes in the earth's 

 surface. Its close was marked by a period of great cold which 

 wrought havoc among vegetation, and even to-day much 

 land that in Tertiary times was forest, is hidden under enor- 

 mous icefields. In those times most of the present Arctic 

 zone was probably free of ice; at any rate Spitzbergen, 

 Greenland, Iceland, the extreme north of the mainland of 

 America and of Asia enjoyed a climate as mild at least as New 

 England does to-day, and vast forests circled the whole of 



to-day's Arctic regions, for the land connection was complete. 

 In those times, too, the types of tree vegetation were similiar 

 throughout the whole Northern Hemisphere. Doubtless 

 then as now species had a limited distribution; but the genera 

 then, much more than to-day, were widespread. Tulip 

 Trees, Magnolias, Sweet Gums, Ginkgos, Sassafras, Sequoias 

 and indeed countless others grew in Europe, in America, and 

 in Asia. 



As the period of great cold came on vegetation was forced 

 to migrate down the mountains and southward to escape 

 destruction. And as the ice crept southward it destroyed 

 the vegetation in its path; the trees of Greenland, Spitzbergen, 

 Iceland and the regions separating North America and 

 Eastern Asia all disappeared. On this continent they were 

 forced south of the latitude of Philadelphia (which is about 

 Lat. 40°N) and where there was no continuous land connection 

 they were destroyed; while on the continent of Europe they 

 were swept almost to the very fringe of the Mediterranean 

 and so nearly destroyed that to-day there are only about 

 three dozen genera of trees to be found there, and even the 

 species are very limited in number. 





THE GREAT OAK AT BLENHEIM, THE MARLBOROUGH ESTATE IN ENGLAND 



The warmth permeating and living in every line and branch of this famous patriarch enfolds like a divine 

 embrace, accounting for the veneration in which all ages of Britons have held these great trees 



