Summary and Conclusions (a) The insoluble residues from the limestones contain detrital quartz, amorphous, cryptocrystalline and microcrystalline silica, siliceous pseudomorphs after organic remains, sponge spicules, fluor, magnetite, pyrites, zircon, ilmenite, tourmaline, muscovite, biotite, and felspar. (b) No megascopic chert occurs. (c) The succession contains more arenaceous and argillaceous rocks than occur in the Avon section. They contain magnetite, rutile, zircon, ilmenite, tourmaline, muscovite, and staurolite among the rarer constituents (d) Oolites have a notably small average percentage of insoluble residues, probably owing to their rapid formation, in clear water. (e) The detrital material in the Avonian rocks of Sodbury has probably been derived, directly or indirectly, from some Pre-cambrian complex to the north or north-west.