This is an area that suffers extremes of climate, blistering summers and vicious winters. There are a lot of fossils.
Weather is what exposes fossils.
Ice cracks rock. Gradually fossilized bone is revealed. So weather is the fossil hunters friend, it reveals what had been hidden. But weather is also the fossil hunters worst enemy because an unfound fossil is gradually erased, just like the rock that surrounds it. Timing is everything.