A quarry site located near Lowbank on the River Murray, 7 miles east of Waikerie, has been geologically mapped and partly explored by drilling 14 vertical diamond holes with a total depth penetration of 702 feet. Marine sandy limestone and calcareous sandstone of the Norwest Bend Formation form a resistant capping about 20 feet thick at the top of the riverbank cliffs, which are 120 feet high. These indurated beds are almost horizontal, and are continuously exposed for 3000 feet along the southern side cliff, at the edge of an elevated plateau. Drilling suggests that the most competent materials, limestone and well-cemented sandstone, occur in a bed 4 to 15 feet thick, which appears to be continuous over the greater part of the explored area. Overburden above this material ranges from zero to 10 feet thick at the cliff edge, up to a maximum thickness elsewhere of more than 40 feet, and consists partly of clays and clayey sands, and partly of sandstone and limestone of poorer quality than the competent bed. Preliminary resource estimates are as follows: (a) Assuming both sandstone and limestone to be of acceptable quality - rip-rap 430,000 cu.yds, and overburden 2,160,000 cu.yds; (b) Assuming the limestone only to be acceptable - rip-rap 80,000 cu.yds, and overburden 810,000 cu.yds. A considerable amount of further exploratory work, including diamond drilling and trial quarrying, will be required if it is proposed to adopt the site as a source for rip-rap material.