ɡlˈoʊbəl kˈuːlɪŋ θɹˈiː.tˈuː dˈæʃ θɹˈiː.wˈʌn mˈɑː tɹˈɪɡɚd ɐ sˈiːlˈɛvəl dɹˈɑːp wˌɪtʃ ɪŋkɹˈiːst ɪɹˈoʊʒən ɪnsˈɪʒən ˌʌp ðə mˌɪsɪsˈɪpi ɹˈɪvɚ ænd lˈɛd tə ðə kˈʌmbɚlənd ɹˈɪvɚ kˈʌɾɪŋ ˌɪntʊ ðə hˈaɪlənd ɹˈɪm ænd ɪts hˈɛdwɔːɾɚz, ðə kˈɑːlᵻnz ɹˈɪvɚ, kˈʌɾɪŋ ˌɪntʊ ðə kˈʌmbɚlənd plætˈoʊ.
Global cooling 3.2-3.1 Ma triggered a  sea-level drop which increased erosion (incision) up the Mississippi River and led to the Cumberland River cutting into the Highland Rim and its headwaters, the Collins River, cutting into the Cumberland Plateau.