In the Portland sandstone, much of the limey mud was laid down with bits and pieces of shells or sand. These became coated with layers of lime mud, and formed small balls (less than 0.5 mm diameter). Over time, countless billions of these balls, known as "ooids" or "ooliths", became partly cemented together by more calcite, to form the oolitic limestone we call Portland limestone.
ɪ n ð ə WORD_BOUNDARY p ɔ ɹ t l ə n d WORD_BOUNDARY s æ n d s t oʊ n WORD_BOUNDARY m ʌ t̠ʃ WORD_BOUNDARY ʌ v ð ə WORD_BOUNDARY l aɪ m i WORD_BOUNDARY m ʌ d WORD_BOUNDARY w ʌ z WORD_BOUNDARY l eɪ d WORD_BOUNDARY d aʊ n WORD_BOUNDARY w ɪ ð WORD_BOUNDARY b ɪ t s WORD_BOUNDARY æ n d WORD_BOUNDARY p iː s ɪ z WORD_BOUNDARY ʌ v WORD_BOUNDARY ʃ ɛ l z WORD_BOUNDARY ɔ ɹ WORD_BOUNDARY s æ n d WORD_BOUNDARY ð iː z WORD_BOUNDARY b ɪ k eɪ m WORD_BOUNDARY k oʊ t ɪ d WORD_BOUNDARY w ɪ ð WORD_BOUNDARY l eɪ ə ɹ z WORD_BOUNDARY ʌ v WORD_BOUNDARY l aɪ m WORD_BOUNDARY m ʌ d WORD_BOUNDARY æ n d WORD_BOUNDARY f ɔ ɹ m d WORD_BOUNDARY s m ɔ l WORD_BOUNDARY b ɔ l z WORD_BOUNDARY l ɛ s WORD_BOUNDARY ð ʌ n WORD_BOUNDARY z iə ɹ oʊ WORD_BOUNDARY f aɪ v WORD_BOUNDARY ɛ m ɛ m WORD_BOUNDARY d aɪ æ m ɪ t ə ɹ WORD_BOUNDARY oʊ v ə ɹ WORD_BOUNDARY t aɪ m WORD_BOUNDARY k aʊ n t l ə s WORD_BOUNDARY b ɪ l iə n z WORD_BOUNDARY ʌ v WORD_BOUNDARY ð iː z WORD_BOUNDARY b ɔ l z WORD_BOUNDARY n oʊ n WORD_BOUNDARY æ z WORD_BOUNDARY uː ɪ d z WORD_BOUNDARY ɔ ɹ WORD_BOUNDARY uː l ɪ θ s WORD_BOUNDARY b ɪ k eɪ m WORD_BOUNDARY p ɑ ɹ t l i WORD_BOUNDARY s ɪ m ɛ n t ɪ d WORD_BOUNDARY t ə ɡ ɛ ð ə ɹ WORD_BOUNDARY b aɪ WORD_BOUNDARY m ɔ ɹ WORD_BOUNDARY k æ l s aɪ t WORD_BOUNDARY t ə WORD_BOUNDARY f ɔ ɹ m WORD_BOUNDARY ð ɪ WORD_BOUNDARY uː l ɪ t ɪ k WORD_BOUNDARY l aɪ m s t oʊ n WORD_BOUNDARY w iː WORD_BOUNDARY k ɔ l WORD_BOUNDARY p ɔ ɹ t l ə n d WORD_BOUNDARY l aɪ m s t oʊ n WORD_BOUNDARY