What is more, some of the pollen grains and spores I found in the clays and lignites came from conifers and tree ferns that could have grown only at the high altitudes of a mountain range.

• 而且我在黏土及褐煤中发现的花粉粒与孢子，属于针叶树及树蕨，它们只生长在高海拔的山区。