The evidence does not  indicate that these trees grew in this area.  They were transported here by current action. Further, it is evident that they were buried rapidly and catastrophically but not slowly and gradually.  Dr. Dale Russell comments, "Clusters of stumps were buried upright, with some penetrating as much as 3 metres of overlying sediment -- in evidence of the rapidity with which sediments accumulated. (Dale A. Russell, An Odyssey In TimeThe Dinosaurs of North America P.31)