Determining the paleoenviroment and tectonic history of a small area (Cocklawburn Beach)

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Geology Coursework                                                 Jonathan Robinson

Geology Coursework: Determining the paleoenviroment and tectonic history of a small area (Cocklawburn Beach)

Planning

In this coursework I am going to try and find the tectonic history and paleoenviroment of an area of exposed rocks along a short section of beach in Northumberland, Cocklawburn beach is 50 metres to the south of Berwick-upon-tweed and can be found on OS map sheet 75. The general geology of the area is that it is mostly carboniferous limestone with layers of sandstone, shale and coal existing between the layers of limestone.  I know this from previous experience in the area, as I have completed a sedimentary log for another section of rock in the same area, at Cullernose Point

        

For the paleoenviroment I am going to look at and analyse the rock type.. I will check the rocks for structures and fossils as they can be used to determine the absolute age of the rocks and they can also be used to check if the rocks have been shifted or if they have been moved upside down. The first thing that I shall investigate with respect to paleoenviroment is the relative age of the rocks. For the tectonic history I shall investigate the Dip and Strike of the rocks, as this will show the attitude of the rocks relative to the horizon and it will show if any tectonic activity has shifted the rocks, and also if there are any major igneous structures (Bowls ect) I shall look for any displacement in the rocks as this will show if there have been any faults in the area that have affected the rocks in the past. Using all of this information together I intend to construct a sedimentary log that will definitively show the history of this small area. To help me find this information I will use my own observations, as well as secondary sources such as the Internet and geology reference books (see bibliography) I think that I am most likely to find Sedimentary rocks that will be in recurring cyclotherms containing a lot of fossils and other structures, and that have also been affected by a lot of faulting and folding.

To collect the data for the items I have outlined above, I will go to the beach and construct a sedimentary log. I have already tested this method on another beach in the same area as Cocklawburn beach, at a area called Cullernose point

This log will encompass most of the data that I will need to collect, however I will also have a Field Notebook, which I will use to sketch out the layers or rock and also to sketch any structures that are found on the beach, this will be used so I can identify which type of fossils and what special features were present in the layers of rock. To fill in the above logging sheet I will use the following equipment. To find the grain size of the rocks, I will examine the rock with a hand lens and compare what I see to a grain size index card provided by my teacher, I will do this to find the energy of the transport medium at the time of deposition, this card will also to be used to checked the sorting of the rock, which will show the rate of deposition. I will look for any fossils in the rock, as they will help to show if there are any special environmental conditions in the area during that time of disposition. I will also use evidence of any sedimentary structures to determine the environment of deposition. I will also examine the colour of the rocks to try and determine the mineral and oxygen content, as this can be used to try and determine the paleoenviroment of the area at the time that the sediment was deposited that formed the rock layers. I will look for evidence of dip and strike by using clinometers to find the dip angle and using a clinometers and a ruler to find the strike, I will do this so that I can accurately show any tectonic features in the area, and so that I can form a hypothesis about what forces have acted on the area in the past. I will look for evidence of folding and faulting, as they will show if there have been any compression or tension forces acting on the rock, and also the direction that the forces were coming from.

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To test these methods I have constructed a short sedimentary log of beach called Cullernose point, which is near Cocklawburn beach, I have found that these methods work in the field and I do not intend to change any of the methods used.

The limits of my investigation if that I can not check any rocks that are underground, so I will not be able to find the thickness of some beds, if I can not see the base.

Implementing

In this section I will record the ...

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