The site of the Callington greywacke deposit, located 2 km south of Callington township, was leased from the landowners by the Readymix Group in 1972 when preliminary geological investigations indicated that it contained unusually massive bedrock that was potentially suitable for the production of construction materials needed for building the new South Eastern Freeway and the planned nearby city of Monarto. The main reason for selecting this site, relative to two others located further north, was the physical nature of the stone, notably its lack of iron or copper sulphide particle impurities, and the fact that it contained only a very small number of thin schistose interbeds. The lessee's subject report, dated 17 July 1978, represents a formal [MARP] proposal to open an aggregate quarry in this selected Kanmantoo Group greywacke. An environmental impact study is presented, which includes as Appendix 3, brief lithological logs of nine vertical percussion drillholes totalling 730 feet that were drilled down to the water table at the proposed quarry site in February 1973. Also included as Appendix 4 are the results of materials durability physical and chemical tests carried out on bulk samples taken from 15 feet deep pits that were dug in two intended priority mining zones within the deposit.