Using three independent methods--isotope analysis of fossil trees and mosses, analysis of the distribution of lipids in fossil soil
bacteria and an inventory of ancient plant distributions--the scientists determined that although the mean annual temperature on Ellesmere Island during the Pliocene epoch (2.6-5.3 million years ago) was about 19[degrees]C higher than today, carbon dioxide levels were only slightly higher than they are at present.
The upper 7 m of the band of fossil soil
, or paleosol, contains more than 0.1 percent carbon, which is an unusually high concentration for Precambrian paleosol, Ohmoto says.
They also analysed carbon isotope ratios in fossil soil
carbonates located above and below the Toba ash from three locations in central India.The latter technique can be used to determine the type of vegetation present at the time, as each vegetation type has a distinct isotope 'fingerprint.'
These are dominated by fossil soil
horizons sandwiched together with pyroclastic lava flows, ash-fall deposits and other volcanic ejecta.
Their analysis of 1,300 fossil soil
samples from sites at or near where human ancestors and their relatives evolved shows that more than 70 percent of the sites had less than 40 percent woody cover, meaning they were wooded grasslands or grasslands.
They analyzed pollen from a marine core in the Bay of Bengal that included a layer of ash from the Toba eruption, and they looked at carbon isotope ratios in fossil soil
carbonates taken from directly above and below the Toba ash in three locations in central India.
They analysed tracers of ancient leaves and of burned organic matter left behind in paleosols (stratum or soil horizon), or fossil soils
, in northern Pakistan.
Adriana Timofiecsyk, agronomist and soil specialist for the Federation, said that the soils that are prevalent in the Cerrado region are what is known in geology as "fossil soils
," which are rich with iron and, surprisingly, adapt well to coffee and other agricultural crops.
Annie has also used fossil soils
to reconstruct the ancient environments and climates that existed during the time of the dinosaurs in Alberta.
Ancient fossil soils
could be found at just about anywhere in the part of the world, at practically every country under its river, volcano and other sediments.
"However, ancient fossil soils
-- the best indicators of ancient carbon dioxide levels in the atmosphere -- suggest only modest levels during the Archean.
Marty asserted that however, ancient fossil soils
- the best indicators of ancient carbon dioxide levels in the atmosphere - suggest only modest levels during the Archean.