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.
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.