The light from the raised area that eventually formed the overhang seems to somehow remain in the upper area of the scene and it's as if the raised area has stopped rolling towards you while at the same time the scene in the bottom of the viewfinder expands downward continuing towards you. The effect is like the light from the top of the scene is suddenly remaining in place while at the same time the light from the bottom of the scene continues forward and down. This effect seems to cause the object to suddenly remain in place and at the same time open wide open.
A very noticeable valley effect is also now seen to the left in the viewer. The object's surface that precedes the raised area somehow now looks like it is a natural part of the valley as well.
The way that the object looks is as if it is some sort of giant snail is extremely pronounced and somehow greatly exaggerated at this point before the "black spot of the shadow," has made it's sudden appearance. Even though the object's