31. The underlying rock is Malmesbury shale with a zone of greywacke and quartzitic limestone. 32. Mesozoic limestones crop out north of the greywacke zone, forming the Northern Calcareous Alps. 33. Only fragments remain of the sarcophagus, which was probably made of greywacke or basalt. 34. In the Haast Schists, the minerals that make up Torlesse Greywacke became coarser grained. 35. The greywacke belongs to the Waiheke group. 36. Waiheke Island is mostly composed of greywacke . 37. Regional parks such as Tawhitokino and Tapapakanga are good places to see greywacke boulder beaches. 38. Goat Rock is such a flat topped sea stack comprised by a block of resistant greywacke . 39. This is composed of laminated mudstone and siltstone with greywacke sandstone and is of Ordovician age. 40. The basalts are interbedded with slate and greywacke , faulted, and intruded by granitic rocks.
