English: Old Greywacke This is a Greywacke on the shore of Lochranza dating from the Lower Cambrian. It was deposited on the bottom of a deep Ocean along with black muds and shales. They form when a large underwater sediment built up then collapsed forcing sediment of varying sizes out into the Abyssal plane. The sediments settle out heaviest first causing fining up sequences, once all is calm there is usual sedimentation again for a few thousand years then it all happens again, causing turbidite sequences. They were laid down when the land mass was at a latitude of 27oN. When looking at geological maps of the island it can be seen that the Dalradian deep marine sediments occur in the northern part. After their deposition as marine turbiditic (or Greywackes), the rocks have undergone metamorphism to produce metamorphosed greywackes and schists. The regional metamorphism was caused from large earth movements and events in particular the Caledonian Orogeny (collision of Laurentia, Baltica and Avalonia with the closure of the Iapetus Ocean). The rocks underwent slight chemical changes with Chlorine giving then a green tint, the Chlorite grade rocks are at the outer edge of the Barrovian Zones. They were heated and compressed up to roughly 400 degrees temperature and 500 kilobars pressure.
Around 60 Ma the Atlantic formed, magma was forced to the surface like blood when skin tears (America split from Europe). Then like a massive spot a Granite Pluton pushed upwards bending the surface rocks and folding and heating them again. The granite core can still be seen today.
This image was taken from the Geograph project collection. See this photograph's page on the Geograph website for the photographer's contact details. The copyright on this image is owned by Ashley Dace and is licensed for reuse under the Creative Commons Attribution-ShareAlike 2.0 license.
šířit – kopírovat, distribuovat a sdělovat veřejnosti
upravovat – pozměňovat, doplňovat, využívat celé nebo částečně v jiných dílech
Za těchto podmínek:
uveďte autora – Máte povinnost uvést autorství, poskytnout odkaz na licenci a uvést, pokud jste provedli změny. Toho můžete docílit jakýmkoli rozumným způsobem, avšak ne způsobem naznačujícím, že by poskytovatel licence schvaloval nebo podporoval vás nebo vaše užití díla.
zachovejte licenci – Pokud tento materiál jakkoliv upravíte, přepracujete nebo použijete ve svém díle, musíte své příspěvky šířit pod stejnou nebo slučitelnou licencí jako originál.
== {{int:filedesc}} == {{Information |description={{en|1=Old Greywacke This is a Greywacke on the shore of Lochranza dating from the Lower Cambrian. It was deposited on the bottom of a deep Ocean along with black muds and shales. They form when a large un
Tento soubor obsahuje dodatečné informace, poskytnuté zřejmě digitálním fotoaparátem nebo scannerem, kterým byl pořízen. Pokud byl soubor od té doby změněn, některé údaje mohou být neplatné.