The Rooftop of Mirkwood--Natural vs. Unnatural

In considering J.R.R. Tolkien's utilization of both the natural and the unnatural in Chapters 6-9 of The Hobbit, I thought of the moment when the Company is traveling through Mirkwood and Bilbo climbs up one of the trees to see how far they were within the forest. Previously, they had encountered the strange magic of the woods.  Bombur, the dwarf, had fallen in a deep trance after falling into the enchanted stream, and the air was heavy and still as if frozen in a terrible gloom.  Yet, once Bilbo had poked his head above the treetops, the magic of the forest was lost for natural beauty.  Bilbo felt the wind on his face and the warm sunlight on his skin.  Butterflies fluttered around him, and for a moment, he had escaped the dark boughs of Mirkwood.

Furthermore, in a moment of foreshadowing, Bilbo considered whether there were any spiders as he climbed up the great oak.  Above the treeline, naturally sized spiders crawled around while below the treeline great, monstrous eight-legged beasts claimed the forest as their home and were wholly and undeniably unnatural.  The clear and cool sky contrasted with the unnaturally stuffy air on the forest ground, stuffy not because of the density of the woods but because of some strange magic on the land.  While all Bilbo could see was the forest, he was removed from it and once again a part of the natural world.

I think this scene is supposed to demonstrate the contrast between the natural and the unnatural worlds.  Mirkwood is an otherworldly place in a land so full of wild and mystical countries, yet it is of a different variety.  It is darker than many of the other lands.  It is not as lovely as Lothlorien or as ancient and wise as Fangorn.  I believe Mirkwood is a forest meant to symbolize fear and confusion.  Not everything makes sense within it, and even that which would seem harmless in the natural world--the squirrels, streams, etc.--are suspiciously ominous.  However, outside of Mirkwood, challenges still await, but these challenges are more natural and less shrouded in mystery and magic.  Bilbo's excursion to the roof of Mirkwood shows just how different the worlds are though separated only by some tree branches.