Do earthquakes explain all those mastodon bones at Snowmass? Not likely, say scientists, although they haven’t completely shelved the idea. And did humans kill a mammoth 50,000 years ago and then cache the meat for later use? Circumstantial evidence of rocks intermixed with bones suggests that was the case. If so, it would rank as one of the major scientific discoveries of the decade, putting people on the North American continent some 36,000 years earlier than what is now generally agreed upon by archaeologists. That intriguing idea also remains on the shelf, just beyond touch for lack of corroborating evidence.