A tar pit occurs when, bitumen, a natural asphalt, rises to the surface. The lighter components in the bitumen vaporize and the remnants, a thick viscous material linger. The bitumen is formed, like most petroleum from living organisms. Upon death they are crushed by the fires of the earth and the weight of time until the undead molasses of their creep is created. Creatures unfortunate enough to fall into the pits rarely escape as the clinging nightmare refuses them life.