summary of the time period The cambrian A2 geology

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  • Created by: rosie
  • Created on: 27-05-11 22:18

The cambrian


the cambrian was the first period of the Lower Palaeozoic, lasting about 30 million years.

the cambrian was between 544Ma and 510 Ma.

The cambrian 'when life appeared in abundance in the Sea! But not the land'.

Four main continents present in the cambrian period =

Where was Britian in the cambrian?
in the cambrian britian was seperated, onto two different continents.
Scotland- part of Laurentia (0 )
England and whales- part of Gondwana (60 s)

A huge 4,500km ocean seperated scotland from England and whales! in the cambrian.( and yet today they are in fact together)

- The iapetus ocean seperated them in the cambrian.

-The iapetus ocean was a spreading ocean in the cambrian( may have once been 7000km wide).Proof =paleomagnetism of new basalt found today as tayvallich basalts. Alwell as the lack of andesitic rock which would suggest subduction and therfore closing.

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Rocks of the Cambrian

So we know that scotland was seperate from the rest of England and whales in the cambrian. this means that diffrent rocks will be seen due to the diffrent environments/climates they were in due to their position.

cambrian Rocks in Scotland.
The durness series ( 1,200m of shallow water limestone's and calcium/magnesium dolomites.)

south east  = subsiding deeper water sediments called the dalradian sequence. this is Greywacke, phyllite and shists. which strech to pre-cambrian to cambrian.

cambrian rocks in North Whales.
Thick sequence of deep marine sandstones and shales. shales now seen as slate.

poorly sorted sandstones and highly angular, formed by turbidity currents. and these sandstones were formed the greywacke.

cambrian rocks in Shropshire and the midlands.
Rock sequence present made of 3 rocks:
1) Firstly beache conglomerate, composed of eroded pre-cambrian material.
2) A thick quartzite sandstone- Wrekin sandstone.
3) Above = Green marine sandstone, Glauconite  called comley sandstone.
and at the top is a thin sequence called the comley limestones containing TRILOBITY.

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Evidence for the location of Britian during the ca

1) the cambrian dated Tayvallich basalt lavas in the Grampians (scotland) show a spreeding ridge/ sea floor spreading during the pre-cambrian aound 595ma. as basaltic lavas for baslatic rocks and come from constructive plate margins, (less contact which the continental crust therefore less silica content).

2) Fossils the trilobites found in Nw scotland, show differences to thoes founf in england and whales. shows they were seperated in the cambrian period. this difference shows that shallow water species were provented from mixing by a deep ocean

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Littered with grammatical and spelling mistakes but some sound revision notes. Who knew that england (sic) was attached to a large marine mammal (whales)?

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