The black substance that trapped the animals came out of the Earth as oil.

VOA: special.2010.04.07

This is important, because it's the black earth region of rich agriculture there.

这是很重要的一点,因为他们住在农业发达的黑土地区

耶鲁公开课 - 欧洲文明课程节选

The group stopped to examine the sticky black substance that covered the Earth.

VOA: special.2010.04.07