Flint circles are even stranger formations usually consisting of a large round flint rim or rind with chalk filling in the middle.
flˈɪnt sˈɜːkəlz ɑːɹ ˈiːvən stɹˈeɪndʒɚ fɔːɹmˈeɪʃənz jˈuːʒuːəli kənsˈɪstɪŋ əvə lˈɑːɹdʒ ɹˈaʊnd flˈɪnt ɹˈɪm ɔːɹ ɹˈaɪnd wɪð tʃˈɔːk fˈɪlɪŋ ɪnðə mˈɪdəl.