106 TREE ANCESTORS 



their leaves are found in Spitzbergen, and at the farthest northern 

 outpost to which temperate forests are known to have penetrated 

 at that or any other time, namely, to within 10° of the pole itself 

 in Grinnell Land, where two kinds of hazel are preserved in rocks 

 that are today covered with perpetual snow and ice. 



These Eocene records are found in a belt between 40° and 80° 

 north latitude, and south of that belt are found traces of a warmer 

 temperate flora — that from the shores of the Mississippi Gulf of 

 that time being sub-tropical. In the present flora of Spitzbergen, 

 among the 130 species of knowoi flowering plants, there is only a 

 single tree genus — Salix, the willow — there only 2 or 3 inches tall. 

 The hazel today ranges from about 31° north (northern Florida) 

 to 55° in North America and to about 60° in southern Sweden. 

 The Middle Eocene was a time of expanded seas and partially 

 submerged continents, and it is believed that the resulting free 

 circulation of the warm ocean waters so ameliorated the chmate 

 that the tropics spread into the present temperate zones and the 

 temperate zones spread far toward both poles, without any sharp 

 contrasts except in the interior of the land masses. This was the 

 time of the mildest and most equable climates known during the 

 whole Tertiary period, but it was far from being absolutely uni- 

 form, or from being tropical in the far north as some rash students 

 have asserted. At the present time the warm drift of the North 

 Atlantic greatly modifies the climate of Spitzbergen, causing the 

 isotherms to extend far north of their average position — the iso- 

 therm of 23° Fahrenheit reaching southern Spitzbergen, and the 

 present cold pole is not at the geographical North pole, but in the 

 severe continental climatic region of northern Siberia. 



Obviously the hazel must have originated in some of these 

 northern lands where it was so widely distributed and abundant 

 in those early days, spreading from thence southward with the 

 changing climates of the Oligocene, but apparently never getting 

 nearer the equator than does our common American hazel {Corylus 

 americana) or than did Corylus australis in the Island of Madeira 

 during Pleistocene times. 



