Ygdrasil Mountain adopted 4 March 1965 on 82N/12, not Mount Yggdrasil as originally submitted in 1954 by William Putnam (file B.1 59).

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

"Mt. Yggdrasil [sic] was so-named as it seemed appropriate to this particular group in which Thor, Woton [sic] and Fria were already named." (Putnam's 1954 letter to Geographic Board of Canada). Note that Mount Wotan, the namesake for Wednesday, was named c1908, but Putnam himself had dubbed Mounts Thor and Fria in 1948, adding those names to his own maps. Mount Thor, the namesake for Thursday, was rejected due to duplication nearby; Frigg - not Fria or Freya as claimed by Putnam - is the namesake for Friday.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

In Norse mythology, Ygdrasil (spelled "Yggdrasil" in some dictionaries), is the great ash tree symbolizing the universe:

"A wondrous ash tree, Yggdrasil, supported the universe. It struck its roots through the worlds.
Three roots there are to Yggdrasil
Hel lives beneath the first.
Beneath the second the frost-giants,
And men beneath the third.
It is also said that one of the roots goes up to Asgard.........
Over Yggdrasil, as over Asgard, hung the threat of destruction. Like the gods it was doomed to die. A serpent and his brood gnawed continually at the root beside Niflheim, Hel's home. Some day they would succeed in killing the tree, and the universe would come crashing down." (Mythology, by Edith Hamilton, Little Brown, Boston, 1942.)

Source: included with note