Answer: shales

AnswerCrossword Clue
SHALESLayered rocks
shaleslayered rock
SHALESSources of oil
SHALESPulitzer-winning TV critic Tom
SHALESTV critic Tom
SHALESPulitzer-winning journalist Tom
SHALESFossil rocks
SHALESSome are bituminous
SHALESSynthetic fuel sources
SHALESTerrigenous rocks
SHALESOil-producing rocks
SHALESRocks formed from clay
SHALESFissile rocks
SHALESFine-grained rocks.
SHALESLayers of rock.
SHALESFissile rocks.
SHALESFossil-yielding rocks
SHALESOil-bearing rocks
SHALESLaminous rocks
SHALESFuel-yielding rocks
SHALESLayered minerals