View this artwork by appointment, at Tate Britain's Prints and Drawings Rooms
There are two sketches, one above the other, showing jagged skylines. They may represent the same currently unidentified range seen from different angles in passing. There is a similar drawing on the verso (D13760). See also the similar profiles on folios 37 verso and 38 recto (D13808, D13809). As discussed in the sketchbook’s Introduction, it is possible that they relate to Turner’s 1817 tour along the River Rhine in Germany.