- Magma flows into gaps in surounding rocks
- Magma solidifies in vertical fissured (across layers of rock)= form thin vertical veins of igneous rock that form when magma enters and cools
- Cut across bedding planes of rock into which they have been intruded.
- Material of dyke usually more resistant- other rocks worn away and dyke is exposed by later erosion.
- Can be many kilometres in length
- Form groups- 'Dyke swarm'
- A major group of parralell/ linear dykes introduced into continental crust
- Example- Fraser Dyke Swarm
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- Horizontal sheet of igneous rock intruded between older rock beds
- Magma flows into gaps in rock and cools horzontally- between laters of rock.
- Example- Great Whin Sill, Northumberland
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- Large chambers of igneous rock- mass of igneous rock, typically diamond shaped, has been intruded between rock strata causing uplift in shape of a dome
- Form deep below the surface
- Several hundred Km long
- Exposed by later erosion
- Batholiths change the rock that they touch- the heat turns it into a different type of rock= metamorphic auerole
- Example- Hambledown Tor, Dartmoor
- Sierra Nevada Batholith USA.
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- Smaller injections of lava
- Lense shaped, between layers of rock- very viscous magma, forces overlying rock to DOME
- Example- Small range of hills 'Eildon Hills' Scottish border
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