Things that are marvelous are typically welcomed and enjoyed.
In this excerpt, the author uses the word "marvelous" to describe the distance occupied by the wider region. He also describes this as "unexplored." The fact that the author uses these words demonstrates that he has a hopeful attitude towards the exploration of this region, as things that are marvelous are usually welcomed and enjoyed.
Homophones
Homophones are words that sound the same, but have different meanings. In this case, "there," "they're" and "their" all have different meanings, but sound the same, which often leads people to make mistakes when using them.
