Part 6/10:
During the Carboniferous period, the composition of Earth's atmosphere was rich in carbon dioxide, allowing trees to flourish and grow larger. At that time, the decomposition processes were incapable of breaking down lignin, a robust compound that provides wood with strength. This incapacity meant that when trees died, their remains often lay intact on the forest floor for extended periods. Eventually, geological activities buried many of these trees, subjecting them to heat and pressure, which transformed them into coal. Notably, this process only occurred during a specific timeframe in Earth’s history—between 380 million and 280 million years ago—implying that trees from later periods will never contribute to coal formation.