11. Instead domestic oil shales were heated to produce the needed petrol. 12. They are underlain by a small ridge of resistant Cretaceous shale . 13. These sedimentary deposits were over time compressed into shale and sandstone. 14. The State Circle Shale is composed of laminated shales and siltstone. 15. The State Circle Shale is composed of laminated shales and siltstone. 16. Flysch consists of repeated sedimentary cycles with upwards shale / mudstone. 17. There are, however, a few small areas of shale . 18. The younger date is from the early Silurian Birkhill shale formations. 19. Calcareous shales from the Canberra Formation is overlain by Quaternary alluvium. 20. The dam foundations are weathered Devonian conglomerates, sandstones and shales .
