What an impressive diabase formation I have found here.
DIABASE, also called Dolerite, is fine to medium grained, dark gray to black intrusive igneous rock.
The veins of black igneous rock found by the shoreline are more than 600 million years old.
Diabase or dolerite or microgabbro is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro.
Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine grained to aphanitic chilled margins which may contain tachylite (dark mafic glass). Diabase is the preferred name in North America, while dolerite is the preferred name in the rest of English-speaking world, where sometimes the name diabase is applied to altered dolerites and basalts. Some geologists prefer the name microgabbro to avoid this confusion.
Molten lava from the earth's depths seeped into a network of fractures and cracks when the St. Lawrence Valley was formed, becoming diabase rock.
Diabase cools moderately quickly when magma moves up into fractures and weak zones below a volcano.
Black rock veins near the shoreline are more than 600 million years old. The molten rock, from the depths of the earth, has infiltrated a network of fractures and fissures at the time of the formation of the current St. Lawrence Valley.
Although dikes may range in size from a few centimetres to greater than 10 metres (about 33 feet) in width, they average between 0.3 and 6 metres (between about 1 and 20 feet) wide. The length of a dike usually depends upon how far it can be traced across the surface; dikes can be up to hundreds of miles long. The world’s longest dike is the Great Dike of Zimbabwe, which stretches for more than 550 km (about 342 miles) southwest to northeast across the centre of the country.
To be able to log this earthcache as found, you need to answer two simple questions and send the answers to me by e-mail.
1 - What is the dominant color of the dike?
2 - Is the vein horziontal or vertical?
3 - Does the dike in comparison to the surrounding rock seem to be porous or solid?
4 - Is this a simple yet impressive dike or an example of a dike swarm.
5 - Optional would be a picture of you or your GPS (or whatever your fancy) near the dike, NOT the dike itself.
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1 - Quelle est la couleur dominante du dyke au PZ?
2 - La vien est-elle horizontale ou verticale ?
3 - La digue, par rapport à la roche environnante, semble-t-elle poreuse ou solide ?
4 - S'agit-il d'une digue simple mais impressionnante ou d'un exemple d'essaim de digues ?
5 - Optionnel, vous pouvez inclure une photo près du PZ de vous et votre GPS ou selon votre imagination...