Intrusive Activity Flashcards
(24 cards)
(1) intro - when did the paleogene period last from?
65 million years ago until 23 million years ago
(1) intro - before the paleogene period…..
Britain, Greenland and North America were all joined together as a large continent and a major intra-plate hotspot developed between Britain and Greenland
(1) intro - what is a hotspot?
A column of super heated magma inside the mantle that rises towards the surface
(1) intro - what did this hotspot cause?
Thermal uplift and eventually continental rifting and a new ocean ridge was formed along with the North Atlantic Ocean.
(1) intro - these huge factors from the hot spot also caused what?
A large amount of associated volcanism in North west Scotland, Northern England and Northern Ireland.
(2) case study: The Whin Sill, Northern England - when did the Whin Sill form and what is it made of?
Formed around 295 million years ago and is made from dolerite
(2) case study: The Whin Sill, Northern England - what did crustal extension allow?
The intrusion of magma between the layers of country rock, forming a concordant intrusion.
(2) case study: The Whin Sill, Northern England - the Whin will reaches a max thickness of……
70m and is found from Holy Island, Bamburgh on the East Coast right across Northumberland.
(2) case study: The Whin Sill, Northern England - the sill is highly resistant to erosion which means what?
As the overlying country rocks have eroded away a number of striking landscape features have been produced.
(2) case study: The Whin Sill, Northern England - what do the landscape features of the whin sill include?
Sea cliffs such as the Farne Islands and Bamburgh castle, waterfalls such as high force on the river tees, and bold escarpments throughout Northumberland.
(3) Case study: Isle of Arran - where does it lie?
Off the west coast of Scotland
(3) Case study: Isle of Arran - what does the northern half of the island include?
The highest peak, Goat Fell, at 874m
(3) Case study: Isle of Arran - this part of the island is made mainly of what?
North Arran granite. It forms a circular body of igneous rock with very coarse-grained crystals, which get smaller towards the edges.
(3) Case study: Isle of Arran - the North Arran granite is…..
A pluton or batholith, approx. 11km across. It was forced into the crust at great depth during the paleogene.
(3) Case study: Isle of Arran - what did the North Arran granite intrusion do?
Deformed overlying country rocks (doming) so the sedimentary layers seen today are tilted away from the batholith.
(3) Case study: Isle of Arran - some of the country rocks closest to the intrusion have what?
Been metamorphosed by heat from it, changing them to metamorphic rocks. The batholith itself has been revealed by extensive erosion of the softer overlying country rocks producing a mountainous landscape in the North of the island.
(3) Case study: Isle of Arran - what is the kildonan shore In the south of Arran?
A sandy beach crossed with many parallel ‘walls’ of igneous rock, acting like groynes. These rocks are a dyke swarm.
(3) Case study: Isle of Arran - these dykes vary in size from….
30cm to 30m wide, and are made from low-silica composition igneous rocks such as dolerite.
(3) Case study: Isle of Arran - over 50 dykes form what?
A striking series of ‘rock’ walls along the shore
(4) EVALUATION - I have shown that what?
Millions of years of denudation of the overlying country rock in this ancient landscape resulted in the formation of a variety of different igneous landscapes in northern Britain.
(4) EVALUATION - the majority of factors that control this include what?
The age of the intrusion, its size and shape, the nature of the weakness it intruded into, and the relationship between the intrusion and the country rock.
(4) EVALUATION - these factors combine to recreate what?
A landscape which is distinctive to the local area and the specific conditions found there
(4) EVALUATION - subsequent climatic changes …..
Will then combine with the local geological conditions over millions of years to shape the landscape.
This process will continue into the future to reveal an evermore distinctive landscape.
(4) EVALUATION - the lack of short term dynamism in the changes what?
Contrast markedly with certain extrusive volcanic features and seismic landscapes which undergo significant modelling with much greater frequency.
