As ascertained by Finberg, this page displays groups of maritime vessels.1 Turner has used much of the sheet horizontally, but inverted relative to the foliation of the sketchbook. A drawing made on the facing page (folio 5 recto; D17373) extends across the gutter, marking the current sheet with the tail end of a slice of topography at far left.
In addition, Turner also makes three drawings on this page with the sketchbook turned vertically. Positioned along the top half of the right edge, each is marked as separate from the rest of the sheet by briefly indicated boxes.
An isolated detail has been composed at far right, towards the centre of the edge of the page. It is comprised of a rectangle on a somewhat diagonal slant, with a smaller shape inside marked by a cross. The source of this small feature is unclear, but it seems likely that it relates to one of the maritime vessels.
Finberg 1909, I, p.607.