fossil charcoal造句

Fossil charcoal is known as fusain, a crumbly silky material which may form blocks or microscopic films.
Eucalypts originated between 35 and 50 million years ago, not long after Australia-New Guinea separated from Gondwana, their rise coinciding with an increase in fossil charcoal deposits ( suggesting that fire was a factor even then ), but they remained a minor component of the Tertiary rainforest until about 20 million years ago, when the gradual drying of the continent and depletion of soil nutrients led to the development of a more open forest type, predominantly " Casuarina " and " Acacia " species.
It's difficult to find fossil charcoal in a sentence. 用fossil charcoal造句挺难的