Quartz keratophyre sills interbedded with folded Devonian sediments in the Annan River tinfield area in north Queensland have probably been intruded when the sediments were unconsolidated or only partly consolidated. The sills are compared with similar occurrences in Wales, Alaska and Australia. Some of these may have been extruded prior to burrowing into sea-bottom muds but the north Queensland examples are probably true, though very high-level, sills.

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