Nora Noffke¹

1 Old Dominion University, Department of Ocean, Earth & Atmospheric Sciences, Norfolk, Virginia 23529, USA

Archean Earth history is very difficult to reconstruct. Until recently, only bacterial cells preserved in chert, microborings, and stromatolites provided the few clues to ancient life. Now, siliciclastic “microbially induced sedimentary structures” (MISS) are adding to our knowledge of both past life and paleoenvironments. MISS rise from the interaction of photoautotrophic microbial mats with physical sediment dynamics in siliciclastic, shallow-marine settings. Archean MISS can be understood through observations of living microbial mats and modern biotic-physical sedimentary processes. Such geobiological studies are key to the interpretation of the early evolution of prokaryotes. For example, the 2.9 Ga Pongola Supergroup, South Africa, includes MISS that possibly point to the oldest known cyanobacterial community preserved in Earth’s history.

Manuscript received 27 December 2007; accepted 23 June 2008.

doi: 10.1130/GSATG7A.1