"The succession of lower Old Red Sandstone rocks found in the Welsh borderland, is reinterpreted to reveal a shifting pattern of facies of far greater complexity than was hitherto realized. The sequence of vertebrate faunas is examined in conjunction with the sediments, and in this way a fuller account is given of theconditions of life of these early vertebrates than was previously possible. The boundary between the Downtonian and Dittonian stages is revised to coincide with the major palaeontological break in the region, and this is shown to approximate to a major lithological break, which is here accepted as the division between the local rock units known as the Downton and Ditton series."

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