The dispassionate tone might make you expect the writing to be bland, but London constructs sentences that give incredibly descriptive accounts of the setting and the main character's response to it. Just feast your eyes on this little jewel: "Day had broken cold and gray, exceedingly cold and gray, when the man turned aside from the main Yukon trail and climbed the high earth bank […] he paused for breath at the top, excusing the act to himself by looking at his watch" (1).
In terms of vocabulary, London is pretty easy to read. His ideas also flow in a logical way. If you look closely at this story (and we hope you do), you find that it's written in very neat paragraphs that are all similar in length. Some sentences can get a little long, but for the most part, London writes lines so punchy and compact they'd make Hemingway jealous.
Take for example the beginning of the story's second paragraph: "The man flung a look back along the way he had come. The Yukon lay a mile wide and hidden under three feet of ice. On top of this ice were as many feet of snow. It was all pure white, rolling in gentle undulations where the ice jams of the freeze-up had formed" (2). A big part of London's genius (and one of the reasons he's still so widely read) is that he really picks his spots when it comes to throwing out a million-dollar word. Yes, he might use a fancy term like "undulations," but he surrounds it with a whole bunch of one or two-syllable words to make its appearance much more effective.