Hi ASA
Here's an abstract from the June 2000 "Geology" Journal...
Life associated with a 2.76 Ga ephemeral pond?: Evidence from Mount Roe #2 paleosol
Rob Rye, California Institute of Technology, Division of Geological and Planetary Sciences, MC 170-25, Pasadena, California 91125, USA
Heinrich D. Holland, Harvard University, Department of Earth and Planetary Sciences, 20 Oxford Street, Cambridge, Massachusetts 02138, USA
ABSTRACT
Dark sericitic material at and near the top of the 2.765 ± 0.01 Ga Mount Roe #2 paleosol in Western Australia contains 0.05-0.10 wt% organic carbon with d13C values between -33? and -51? PDB (Peedee belemnite). Such negative isotopic values strongly indicate that methanotrophs once inhabited this material. The textures and the chemical composition of the dark sericitic material indicate that the methanotrophs lived in or at the edges of ephemeral ponds, that these ponds became desiccated, and that heavy rains transported the material to its present sites. The discovery of methanotrophs associated with the Mount Roe #2 paleosol may extend their geologic record on land by at least 1.5 b.y. Methanotrophy in this setting is consistent with the notion that atmospheric methane levels were greater than or equal to 20 µatm during the Late Archean. The radiative forcing due to such high atmospheric methane levels could have compensated for the faint younger sun and helped to prevent massive glaciation during the Late Archean.
Adam: To me this is suggestive of a Concordist scenario in which the Earth is enshrouded in aerosols formed from photochemical reactions on methane in the upper atmosphere, thus covering the heavens but allowing light to pass through producing a diurnal cycle. It's believed that the Sun's UV production is decreasing over the aeons so in the late Archean upper atmospheric processes would have been greater than the present day. Also methane implies life since that's about the only way it can be produced in sufficient quantities under so much photochemical breakdown.
Prior to methane being the major greenhouse gas perhaps the Earth was covered in carbon dioxide ice clouds which would act as infrared heat traps, allowing liquid water oceans in the first aeons of the Dim Sun, but would totally obscure the heavens. Thus the first creative act of God in Genesis, the creation of the diurnal cycle might imply the creation of life - the methanotrophic ecosystem - that preceded the rest of Creation?
Adam
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