Why does the author use the word "peetrified" instead of "petrified" in this sentence?

"He would tell stories of glass mountains' "peetrified" birds singing "petrified" songs, and talk about the days when Pike's Peak was just a hole in the ground."

In this account of James Bridger's life, the use of irregular spelling on the word petrified (peetrified) might have been used to refer to Briger's accent (his way to pronounce things) when it came to this word. Taking into consideration that, depending on the place, the English language is used and adapted in different ways, we can conclude that this was not only the way that James pronounced it, but also the people who lived in the frontier at the time.