Final answer:
The excerpts reviewed suggest thoughtful contemplation and varied personal experiences by the sea but do not provide the name of the girl or details about what she writes in her journal. The sea serves as a powerful metaphor and muse for the characters, inspiring moments of self-reflection and personal insights captured in writing.
Step-by-step explanation:
The narrative in question appears to take on a poignant and introspective exploration of characters who are by the sea. The subjects of these excerpts are various; however, none specifically names the girl who sits on the stairs by the beach. Instead, we encounter different characters, each with their own story and depth. The girl at the beach mentioned in the question could be symbolic of these characters who observe, reflect, and find a connection with the sea, a recurrent theme in literature for its metaphorical significance of depth and mystery.
From the provided excerpts, it is clear that the act of writing in a journal could emulate a personal introspection or an attempt to capture the essence of the sea and its surroundings. These characters could be writing about their internal monologues, their observations of nature, or the intimate events in their lives such as the doting mother and her child Carin, the reflective individual noting a lady's presence by the sea, or even the girl admiring the bright pink shell.
While we cannot specifically name the girl in the journal nor dictate her written musings without further context, it is evident that the sea serves as a muse for self-reflection and contemplation, influencing the characters to feel, express, and write.