Greenland was once upon a time a tropical country. That is proved absolutely by the remains of an extensive tropical flora which are found there. Where now a sheet of solid ice over a mile thick covers mountain and valley, and mighty frozen rivers called glaciers make their way to the sea and hatch icebergs, there was in earlier days a verdure-clad wilderness of luxuriant vegetation. Together with the palms and tree ferns, there were trees related to the giant sequoias of our own west coast; also representatives of the "gingko," the sacred tree of Japan and of the Eucalyptus family, which today is restricted to Australia. Climbing vines festooned the trunks of these monarchs of an ancient forest with draperies of foliage, while close to the ground grew those curious dwarf trees called "cycads," somewhat resembling palms in miniature, in the midst of a tangled undergrowth of ferns and other flowerless plants that carpted the densely wooded areas.