The symbology on the map that denotes a cliff top and bottom has changes over the years. Over time, there is usually a heavy line at the top and bottom, earlier maps have striations from the top towards the bottom usually thicker at the top and getting thinner before running out before the heavy line at the bottom. Sea Cliffs often have multiple edges as landslips and rotational slumps that have happened at different times are at different positions down the slope. This can make the map more confusing to interpret. When you zoom in on older maps you will see more detail and hatching may have been added, it will however always be darker towards the top.
On later maps the top of the cliff is denoted by a heavy crag line at the top, a dotted line where the steepest part of the “Cliff” finishes and then a heavy line at the bottom that is usually the Mean High Water line. There are lines running top to bottom on the more zoomed out maps but these details do not appear on the more zoomed in maps, probably as they are cosmetic and don’t refer to real life features.