This sketch, of the right-hand part of the scene, has notes to remind the artist about particular things in the scene, such as the thin dark band in the sea on the horizon, the foam on the edge of the waves. Instead of spending time sketching in these finer details, the artist has elected to rather put them into words.
Now take a look at the sketch on the next page (step 4), also of the right-hand part of the same scene, but by a different artist. You'll see that the artist's attention was focused closer in, on the end of the mountains, and at where the mountains meet the sea, with little attention being paid to where the sea meets the sand in the foreground (there's a basic indication of colour and a note "small waves").
