In Pages, if one adds a WYSIWYG block with a picture, right or left alignment is used, and the picture is taller than the text, the picture breaks out of its block into the block below.
Using picture alignment also breaks the formatting of other blocks blow it if the picture is too large. In the picture below, "My Articles" and the first article should be aligned directly under my picture.
Reducing the size of the picture to the same height as the text fixes things.