If you look at the trees in Spirit Lake that were knocked down and fosslilized by the erruption of Mount St. Helens in the 1980s (forget exact year), you can see exactly how this can happen. The trees in the lake also match in how they have most roots, branches, and bark removed from the trees just like most polystrate fossil trees that are assumed to be millions of years old and to have died in place.

There is even coal forming at the bottom of the lake.