lˈuːs ænd ʌŋkənsˈɑːlᵻdˌeɪɾᵻd, ðeɪ ɪɹˈoʊd ɹˈæpɪdli, kˈɜːɹəntli æɾ ɚɹˈaʊnd fˈoːɹ.fˈaɪv mˈiːɾɚz ɐ jˈɪɹ, ɔːlðˈoʊ ɛnvˈaɪɹənmənt ˈeɪdʒənsi stˈʌdiz fˈaʊnd ðæt hɐdbɪn lˈɔst bᵻtwˌiːn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti tˈuː ænd tˈuː θˈaʊzənd sˈɪks æɾɚ ɹˈeɪt əvə jˈɪɹ.
Loose and unconsolidated, they erode rapidly, currently at around 4.5 metres a year, although Environment Agency studies found that  had been lost between 1992 and 2006 at a rate of  a year.