Definitions
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun geology A hard dark
sandstone with poorly sortedangular grains ofquartz ,feldspar , and small rock fragments in a compact, clay-finematrix .
Etymologies
from Wiktionary, Creative Commons Attribution/Share-Alike License
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Examples
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West of the Alpine Fault, the rocks of South Westland consist of a basement of Ordovician greywacke with some high temperature metamorphic rocks and granites, and minor areas of younger Cretaceous and Tertiary sedimentary rocks along the coast.
Te Wahipounamu (South-West New Zealand World Heritage Area), New Zealand 2008
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On its eastern margin in Mount Cook National Park, the schist gradually changes back into Permian-Triassic greywacke of a separate terrain.
Te Wahipounamu (South-West New Zealand World Heritage Area), New Zealand 2008
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The bulk of underlying rocks (slates and greywacke to greenschist facies) are marine Silurian, Devonian and Carboniferous sediments of the Hodgekinson Basin and Broken River Embayment.
Wet Tropics of Queensland World Heritage Site, Australia 2008
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The rocks of the North Island's rugged axial ranges are older, brittle, sedimentary rocks (greywacke and argillite) that broke up into a series of blocks (or ranges) along major fault lines as they were uplifted.
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Rock type varies considerably in this region, from the brittle greywacke of the Alps to metamorphosed schist and granite near the Alpine Fault through to a variety of sedimentary rocks (e.g. sandstone, siltstone) along the coast.
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Eastwards, a Permian terrane of greywacke sandstone becomes progressively more highly metamorphosed to become schist which forms the Southern Alps contained within Mount Aspiring National Park.
Te Wahipounamu (South-West New Zealand World Heritage Area), New Zealand 2008
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These predominantly greywacke mountains are higher than others in the region.
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More specifically, this ecoregion is composed of metamorphosed Mesozoic greywacke sandstone, siltstone, and marine volcanics overlain by Miocene intrusives, Pliocene marine and terrestrial fine-grained sediments, and Quaternary lavas and pyroclastics.
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The parent rock is predominantly schist with only minor intrusions of greywacke.
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They are a series of giant alluvial fans made up of coarse greywacke-derived gravel, up to 500 meters (m) deep in places, and overlaid with loess.
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