Final answer:
Dover Beach was written by Matthew Arnold, an English poet known for addressing themes of human despair and the decline of faith. Immortality and Growing Old are not well-known works of Arnold, and there might be some confusion regarding their attribution.
Step-by-step explanation:
Dover Beach is a well-known poem written by the English poet Matthew Arnold. Arnold's work often explores themes of human misery, the retreat of faith, and the constant struggle that is inherent in life. Immortality and Growing Old, on the other hand, are not explicitly attributed to Arnold. It seems that there might be some confusion with the titles or attribution because, to my knowledge, these are not known as his works. It's possible that other authors or texts have been mixed up in this question.
Concerning the mention of Elizabeth Beardsley, it's worth noting that her reference to Reverend James Hervey's Meditations and Contemplations does touch upon themes similar to those found in Arnold's poetry, such as the fleeting nature of life and beauty, as well as the downfall and decay that are part of the world's natural order.