An investigation of beach-sand heavy-mineral deposits between the mouth of the Clarence River in northern New South Wales, and North Stradbroke Island in southern Queensland, was made by the Bureau of Mineral Resources during the years 1948 to 1950. The work done between the mouth of the Clarence River and Southport comprised detailed boring and sampling of beaches and coastal dunes and portion of coastal plains up to a mile or two inland. The levels of the bore-collars were determined in relation to high water mark on the beaches. On North Stradbroke Island, boring was done by Zinc Corporation and a reconnaissance geological investigation by the Bureau of Mineral Resources. The results of this work are being published by the Bureau, and portions of it which have a bearing on the changing sea-levels are summarized below.