Historical Geology Understanding Our Planet\'s Past

required for such a random event would involve billions of years. Moreover,

evidence gathered from ancient rocks on Earth, the Moon, and meteorites

suggests that the amount of ammonia and methane assumed to be in the pri-

mordial atmosphere was not nearly as abundant as originally thought.

Biophysicists,who study the mechanics of life, have discovered intriguing

evidence in the interior of the 4.5-billion-year-old Murchison meteorite, named

Figure 12A spark
discharge chamber
represents prebiotic
conditions on the early
Earth.

Historical Geology

*6 dpi-10%*6 dpi-10%*6 dpi-10%

*6 dpi-10%*6 dpi-10%*6 dpi-10%

*6 dpi-10%*6 dpi-10%*6 dpi-10%*6 dpi-10%

Water

Amino acids

Heat

Circulating

cool water

to condense

steam

Electrodes to

produce spark

Methane,

ammonia,

and hydrogen

Steam