A possible quarrying site for concrete aggregate, within Upper Cambrian quartzites exposed in a cliff located half a mile downstream from the Middle River Dam site, was previously described briefly in the progress report on Middle River Dam dated December 1964. In a letter dated 17th March 1965, the Engineer-in-Chief requested that a more detailed investigation of it be done. It is proposed that the site be used as a source for about 10,000 cu. yards of coarse aggregate to be used in making the concrete for the dam and appurtenant works. A draft specification for the proposed dam requires that its concrete shall be of three classes, each having a minimum strength of 3000 lb./sq. in, at 28 days. Class A – maximum aggregate size ¾ in Class B – maximum aggregate size ½ in Class C – maximum aggregate size 3 in The proposed quarry site has been explored by two diamond drillholes, 70 feet and 80 feet deep respectively. It has also been geologically mapped on a scale of 1 inch = 20 feet. This report describes briefly the results of the above work, and recommends further studies which should be undertaken if the site is to be adopted as a source of coarse aggregate for the dam.