Possible Clues:

• Thus the black snake may stop on the road
• A tar containing a measure of acidity?
• Dark natural pitch
• On which one might drive and sleep outside during a stop?
• Will that black snake stop over the road?
• Petroleum by-product
• That's enough to make the serpent stop on the street
• Will the snake stop all over the road?
• Mixture of tar and gravel used in road surfaces
• Lot surface