MICROBIAL LIFE IN DEEP GRANITIC ROCK

In recent years, there has been rapid increase in the numbers of the p ublished papers on aspects of the microbiology of subterranean environ ments. There has been a significant expansion in the understanding on microbial ecology in shallow ground water systems down to some 50-100 m, accurately reviewed by Ghiorse and Wilson (1988) and Matthess et al . (1992), and our knowledge is currently increasing about deeper crust al environments (Fredrickson and Onstott; 1996, Pedersen, 1993a, 1996; Stevens and McKinley, 1995). Deep subterranean environments vary cons iderably in composition, from soft sandstone and hardened sedimentary rocks to very hard igneous rock types. Here, microbial life in one of the hardest and most common rock types of the earth's crust, granite, is discussed.