Chinese uses reduplication of verbs and adjectives all the time, but I can't find any explanation of reduplication of nouns to explain 小时小时 in this sentence:
(from a Mandarin Companion reader, 地心游记, chapter 5. Our heroes are out of water...)
I interpret 半个多小时 as "more than half an hour" (but less than an hour). What does the repetition of 小时 mean here?