What on earth is happening in this old photo?!?

I stumbled on this photo today in the Washington State archives and, well, I have no idea what the hell is going on here.

Let see if the archive's description can shine any light on it: Shows 16 men standing on top of a log resting on a railroad flatcar, along with a dog and a bicycle. The train car is labeled Northern Pacific 69318'. A bear den is visible inside the log, and 2 openings. A man stands inside the opening to the right."

I mean, OK, yes, that is a description of what the photo shows. BUT WHY?!? It gets stranger the longer you look at it. Why are all those guys standing on top of that log? Why is the log on a train? Why is there a bear inside the log? And why did that one guy haul his bicycle all the up on top with him?

It was published between 1907 and 1915 by Lowman & Hanford Co. in Seattle. That's where my clues run out. I welcome your theories and your photo captions.