Tarry, Road-Surfacing Material
Puzzle 5 of City Nicknames Hard Pack
Question is: Tarry, Road-Surfacing Material
and the answer is: BITUMEN
Word Meaning:
BITUMEN — A sticky, black, highly viscous liquid or semi-solid form of petroleum, burning with a bright flame. It occurs as an abundant natural product in many places, as on the shores of the Dead and Caspian Seas. It is used in cements, in the construction of pavements, etc.; Mineral pitch.
Definitions from Wiktionary.