Such floods often repeat themselves several times per decade, particularly in a basin area which is sinking. Each repetition would leave one layer. All known upright fossils were buried in days, a year or so, or else periodically across perhaps a few decades. They occur all over the world, because swamps, river deltas and volcanoes also occur all over the world. A modern example of slow burial is this forest , which is turning into this marsh .
Wood buried in such marshes is almost immune to rot.
When Mount St. Helens erupted several hundred years ago, the debris flow buried trees. Those buried trees are just like the ones found at Specimen Ridge in Yellowstone National Park. There are at least three lines of argument against this. The first argument is that the fossils aren't all found on one single level of the Geologic Column. Some are from the Devonian Period, well before the dinosaurs.