case studies

• Mt Vesuvius is a strata-volcano with a caldera that spans 610km wide. Originally it had a pininian eruption and is in between the African/Eurasian plate
• 1883 there was the eruption of Krakatoa in Indonesia which left a 7km wide caldera
• an example of a sill is hadrians wall. It was built during the roman empire along a natural line of north facing cliffs formed by the great Whin sill. Roughly 70m deep and dips gently to the south beneath the overlying sedimentary. The cliff is very steep due to the near vertical joints in the basalt.
• the batholith example is the Cornubian batholith which is 280 million year old granite at lands end.
• hawaii- hotspots

  The pacific plate moves northwest over the Hawaiian hotspot at approximately 10cm a year. Basalt is released which accumulates after successive eruptions to create the islands. The active peak Mauna Loa reaches 9000m from the ocean floor. The older islands are no longer active as they move north west beyond the surface the source of the magma. Without new eruptions to add mass, weathering and erosion break down the dormant volcanoes, forcing them below sea level. The newest volcano is 30km SE of hawaii and will eventually rise as a new island.
• The yellowstone caldera was formed 2.1 million years ago-630,000 years ago. Other eruptions are hard to identify as the above mentioned eruptions destroyed any evidence. In each eruption the ash is known to have covered most of the western half of USA whilst fine particulate matter travelled the world and likely decreases global temperature