Apparently what happened was that water collected on these tar pits, and the bigger animals like the elephants ventured out on to the apparently firm surface to drink, and were promptly bogged in the tar.
瀝青坑里積存了水,大象那樣的大動物冒險到似乎堅(jiān)固的水面上去飲水,立即掉進(jìn)了瀝青坑。