Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

Lamson wants to know why gravity only caused the top of the bag to fall in this other picture. The reason is that it was a manufactured bag with a lot more tensile stiffness than shipping paper. The top of the bag fell over because that's where most of the weight of the bag was because it was a pyramidal bag. That's where most of its mass was. The skinny part of the bag below was light enough that the tensile strength of the material was enough to counter the pull of gravity on that light portion of the bag. It's stiffness exceeded its heaviness.