Final answer:
To locate petroleum, one would explore a sedimentary rock layer that is younger than fish fossil-containing layers, focusing on areas near long-standing bodies of water where organic material naturally accumulates.
Step-by-step explanation:
To find petroleum, one would first look for it in a rock layer that is younger than the rocks containing fish fossils, as indicated by the question. Since petroleum is formed from the breakdown of microscopic plants and animals in the oceans and can migrate from its place of origin, geologists typically search within sedimentary rock layers. These layers are younger than surrounding material, and they can contain organic materials that, over time, have been covered by layers of silt and rock, potentially leading to the formation of petroleum deposits.
When looking for petroleum, geologists also consider the environment where the original organic matter was deposited. For instance, sedimentary layers next to bodies of water can be rich sites for exploration due to the accumulation of deceased marine organisms that have settled and potentially transformed into petroleum over millennia. The fossil record can provide clues to the appropriate layers and historical environment that might indicate the presence of petroleum.