The coolest and most surprising part is that the tar pits are still there! Apparently the seeps have been there for tens of thousands of years. [0] (Fun LA tourist activity: jump in yourself and contribute to the fossil record.)
I was similarly surprised to find that something similar occurs on the floor of the Gulf of Mexico. This came to many people's attention after the Macondo well blowout. [1]
[0] https://en.wikipedia.org/wiki/La_Brea_Tar_Pits
[1] https://www.sciencedirect.com/science/article/abs/pii/S09670...