Forms of INtrusive activity

• 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'

Dyke Swarm

• A major group of parralell/ linear dykes introduced into continental crust

• Example- Fraser Dyke Swarm

• 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

• 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.

• 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