flˌʌktʃuːˈeɪʃənz ɪnðə lˈɛvəl ʌvðə ɹˈɪvɚ, pɚtˈɪkjʊlɚli tˈaɪdəl ˈækʃən ɪnðə lˈoʊɚ ɹˈiːtʃᵻz, bɹˈeɪk ˌʌp ðɪs ˈaɪs, ænd lˈɑːɹdʒ ɐmˈaʊnts ʌv flˈoʊ ˈaɪs pˈaɪl ˌʌp ɐɡˈɛnst ˌɛni ˈɑːbstəkəl ɪnðə tʃˈænəl.
Fluctuations in the level of the river, particularly tidal action in the lower reaches, break up this ice, and large amounts of floe ice pile up against any obstacle in the channel.