As further evidence of this theory, it appears that a large amount of char was deposited right before the mass extinction, which could have come from the combustion of coal.
Reasonable mechanisms have been derived for the formation of the major gaseous products and for the deposited char, which appears to be a polymer derived from para-methylbenzonitrile.
Many of the chars in Assam are islands in the Brahmaputra River and can disappear over time due to floods, just as regularly as new char islands form from silt deposits.
Excavators also claimed to have uncovered ash deposits consisting of charred animal bones and stones indicating that Peking man had learned to use fire for lighting, cooking, and heating.
Only minor charring is visible above the deposits, but significantly carbonized parts are found buried in the deposit.
It is highly unlikely that these fires were caused by ashfall, however, as charred material is not found with deposits of this fine-grained volcanic ash, which was almost certainly cooled in the atmosphere before falling.
Islands and sizable newly deposited lands (chars) in the river appear and disappear seasonally.
What remained by midafternoon was a soggy heap of charred material that was deposited on a table in the middle of the cathedral.
In models that aim at predicting the temperature time history of fuel particles, from the injection position to the deposit surface, the information about the char combustion rate is essential.
Trouble with solid deposits can arise if sticky tars condense at the walls and collect char powder from the gas stream.
