What is the importance of Chesil Beach in the novel, On Chesil Beach?

The real-life Chesil Beach in Dorset, on the south-west coast of England, is one of the few shingle beaches in the UK (that is: a beach composed of rocks and pebbles, rather than of sand). Its combined view of the sea and rock-based composition are important metaphoric foundations of several narrative elements, in the present-time sections of the narrative, representing openness, in the case of the former; and the difficulty / slippery footing associated with reaching that openness, in the case of the latter.