ɐn ɛkstʃˈeɪndʒ ʌv fˈʌŋkʃən tˈʊk plˈeɪs ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti wˈʌn, ʃˈɪftɪŋ θˈɜːməl ˈɛnɚdʒi tə blˈæk pˈuːl ænd nˈɪɹbaɪ ɐbˈɪs pˈuːl, kˈɔːzɪŋ ðˌɛm tə hˈiːt ˈʌp.
An exchange of function took place in 1991, shifting thermal energy to Black Pool and nearby Abyss Pool, causing them to heat up.