"So we have a mule and we have a man hollering timber and still no explanation of Mountain jack. Mule skinners were the ones driving the mules right? So they would not be lumber jacks. Yet here is one hollering timber. Why is that?"

Traditional logging, at least around here, is more than just cutting down a tree. You have to get the logs out of the woods. Think crosscut saws and teams of mules or oxen pulling whole trees attached by heavy chains. (If you're in New England, this weekend is the Common Ground Fair , run by the Organic Farmers of Maine. They'll be demonstrating the mule and oxen teams all weekend.)

Loggers worked in gangs, all male, for long stretches in the woods, doing dangerous things. Sorta like landlocked sailors, with in-town reputations to match. Loggers were muleskinners when they had to be. According the to the Wiktionary, "jack" can be anything male, both loggers and mules. English has a wonderful trick of turning a blended image into a single word.